If you only changed the password for a Gmail account then this only affects this account and not other accounts like a Firefox Account where you used this email address as user name, so you should still be able to login to the Firefox Account with the same email and password. Note that you can add a second email address that can be used in case you lose access to the primary email address. ----- *https://support.mozilla.org/en-US/kb/change-primary-email-address-firefox-accounts *https://support.mozilla.org/en-US/kb/add-secondary-email-address-firefox-accounts *https://support.mozilla.org/en-US/kb/forum-response-firefox-sync-verification-email-faq