Sign out of all Google accounts

Sign in to the account you want to use first

Sign in to any additional Google accounts after that

Open Gmail, Google Drive, or another Google service to confirm the first signed-in account is the default

On mobile, remove all Google accounts from the app or device

Add the desired default account first

Add the other accounts afterward

If needed, set the preferred account as the primary account on your device

Clear browser cookies if the old default account still appears

Reopen Google and sign in again in the correct order