Decide which Gmail account opens first

Gmail has no setting called "default account". With several Gmail accounts signed in to one browser, the default is simply the account that was signed in first, and the only way to change it is to sign out of all accounts and sign back in, starting with the one that should open first. That takes about two minutes. The rest of this guide covers the exact steps on a Mac, the separate "default From address" that Gmail does offer as a setting, why the change seems to undo itself, and three ways to make the choice stick for good.

How Google decides which account is the default

Google's help center explains the rule in one sentence: in many cases, the default account is the one signed in with first (Google Account Help: sign in to multiple accounts at once). There is no ranking and no toggle. The first account to sign in takes position zero, and every account added later through Add account is placed after it.

That position shows up in the address bar. The first account's inbox is at a Gmail address ending in /mail/u/0/, the second ends in /mail/u/1/, the third in /mail/u/2/. Typing the plain Gmail address, or clicking a Gmail bookmark that has no number in it, always lands on u/0. That is the inbox that "opens first".

The same help page notes a second effect that matters for privacy. When Google cannot tell which account is in use, for example when a new browser window opens with several accounts signed in, it may apply settings from the default account, such as Web and App Activity and ads personalization. So the default is not only about which inbox appears. It also decides whose settings apply when the context is unclear.

The practical rule: whichever account should open when typing the plain Gmail address must be the first one signed in after a full sign out.

Step by step: change the default account on a Mac

These steps work in Chrome, Safari, Firefox, Edge, and Arc, since they use Google's own account menu rather than a browser setting.

1. Open Gmail in the browser where the default should change.
2. Click the profile picture or initial at the top right.
3. Choose Sign out of all accounts. Google lists this option alongside Sign out in its help (same Google help page).
4. On the sign in page, sign in to the account that should be the default.
5. Open the profile picture menu again, choose Add account, and sign in to each remaining account in the order wanted.
6. Type the plain Gmail address into the address bar and confirm it opens the intended inbox.

Before step 3, check two things. Each account needs a working second factor nearby, such as a phone or security key, because signing back in to several accounts triggers several verification prompts in a row. Google's help page also advises having backup verification methods set up before signing out. And any unsent draft in an open Gmail tab should be saved first, since all tabs lose their session at once.

Do this once per browser and per profile

The order is stored in each browser's cookies. Changing it in Chrome leaves Safari unchanged. Inside Chrome, every profile has its own cookies, so each profile keeps its own default. If the plain Gmail address still opens the wrong inbox, the most common reason is that the change was made in a different profile or browser from the one in use.

Which account should be the default

The order is a choice worth a minute of thought, because the default receives every link that does not name an account. That includes Drive, Docs, Calendar invites, Meet links, and Google search itself.

A useful test is to ask where most unlabeled links come from. For someone whose colleagues share Docs and Meet links all day, the work account should sit at u/0, since those links would otherwise land on the personal account and show a request access screen. For someone who uses a work account only for a few emails a day, the personal account can stay first, and the work inbox can be reached through a numbered bookmark.

Privacy is the second factor. Because Google may apply the default account's activity and ads settings when the account in use is unclear, some people prefer the account with the stricter settings to be the default. That is a judgment call, and the help page linked above is the place to read exactly which settings can carry over.

The third factor is how often the order gets reset. On a Mac that clears cookies on a schedule, or with a privacy extension that deletes cookies, the default will be reset often, and that is a sign to use one of the approaches that do not depend on order, described further down.

A quick check before signing out

Open the account menu and write down the accounts in the order they appear, with their numbers, by hovering or opening each inbox and reading the address bar. That record makes it easy to rebuild the same order, or a better one, after signing back in. Also close or save anything in progress in Docs and Sheets, since those tabs will need the account to sign in again before they can save.

The setting Gmail does have: the default From address

Many people searching this question actually want something slightly different: replies and new messages should go out from one address by default. Gmail does have a setting for that, inside a single account.

In Gmail, click the gear icon, choose See all settings, and open the Accounts and Import tab (shown as Accounts for some work accounts). The Send mail as section lists every address the account can send from, and the address marked as default is used for new messages. Google documents adding addresses in this section and notes that up to 99 different addresses can be used for sending (Gmail Help: send emails from a different address or alias).

The same Google page has a warning worth reading before changing this. To always send from the other address, both the default From address and the default reply-to address need to change. If only the From address changes, replies still go to the original Gmail address by default.

What should be "default"	Where it is decided	Changes by
Which inbox opens first	Sign in order in that browser	Sign out of all, sign back in
Which address new mail is sent from	Send mail as, in one account	Settings, Accounts and Import
Which app opens email links on the Mac	Default email reader in Apple Mail	Mail settings, General

The third row covers the email links on web pages. On a Mac, Apple Mail's settings decide which app handles them; Apple's guide lists this as the Default email reader option on the General pane (Apple Mail User Guide: General settings). Setting it to a browser makes those links open in that browser, but the browser then opens them in whichever Gmail account is at u/0.

Why the default seems to change back by itself

A default set correctly can still appear to drift. Four causes explain nearly every case.

A full sign out happened somewhere. Choosing Sign out of all accounts, clearing cookies, or a privacy extension that deletes cookies on exit all reset the order. The next account to sign in becomes the default, often without anyone noticing which one it was.

A password change or security check. When Google asks one account to sign in again, that account can end up in a different position after it comes back. If the inbox order looks different after a security prompt, repeat the reset.

The wrong browser or profile. The default is per browser and per profile, as described above. A link opened from another app goes to the system's default browser, which may not be the browser where the order was fixed.

A link that names an account. Some Google links carry the account in the address. A link copied from the u/1 inbox and pasted into chat opens under u/1 for the person who copied it, but under the receiver's own u/1, which may be a different account or none at all.

Three ways to make the choice stick

Signing in again in the right order works until the next full sign out. These approaches avoid depending on order at all.

Bookmark each inbox by number

Create a bookmark for each account's inbox using its numbered address, and name it after the account, for example "Work mail" for u/0 and "Personal mail" for u/1. Opening a bookmark goes straight to that account's inbox. The weakness is that the numbers move whenever the sign in order changes, so the bookmarks must be checked after any reset.

One browser profile per account

A Chrome profile has its own cookies, so a profile signed in to only one Google account has nothing to choose between. Google describes profiles as a way to keep accounts such as work and personal separate (Google Chrome Help: manage multiple profiles). Create one with the profile picture at the top right of Chrome and Add Chrome profile. Safari offers the same idea under Safari, Settings, Profiles. Each profile opens in its own window, so the inbox in that window is always the same account.

The cost on a Mac is that all Chrome profiles share one application and one Dock icon, and links from other apps open in the last used Chrome window. Giving each profile a distinct color theme helps, because the window color then shows which account is in front before any page has loaded. Profiles also keep their own extensions and bookmarks, which suits a work account that needs a company password manager the personal account does not.

One app per account

An app aggregation browser for macOS goes one step further and gives each web app its own container and sign in, placed side by side in one sidebar. Gmail for work and Gmail for personal become two separate icons, each permanently signed in to one account, so there is no default to manage. The Workspaces page explains how apps are grouped, and the FAQ answers how several accounts of one service stay signed in at once. On that product, multiple accounts of the same service are a paid feature, also available during the trial; the Pricing page has the details.

What to change first

Sign out of all Google accounts in the browser used most, sign back in with the account that should open first, then add the others with Add account. If the default needs to survive resets, move the second account into its own browser profile. When four or more accounts stay open every day, set up each one as its own app in SpaceDeck.