No such thing as a "Mozilla cloud account". Mozilla does have "Sync" for Firefox, and has other "services" that use the same registration setup as Sync uses. https://support.mozilla.org/en-US/kb/access-mozilla-services-firefox-accounts You may have been using '''Sync'''. See this KB article to learn how to connect to Sync as a "new device" if you're using a different device now, or have a new Firefox installation or Firefox user Profile: https://support.mozilla.org/en-US/kb/how-do-i-set-sync-my-computer You will need the '''email address''' that you originally used to setup Sync ''(aka your "Firefox Account")'' and the '''Password''' that was last used for that account. The Password has to be the correct one for when you last used Sync; the encryption "key" (for your data ) is derived from the Password. Change that Password and your ''"saved"'' data becomes worthless'' (no way to decrypt it without the original password, when it comes back to your device)'', and would have been deleted if / when the Password was reset. ''Note: If you can't remember your Password and decide to '''reset''' it; "kiss your data goodbye". A frequently made mistake that Sync users who think it is a "cloud service" make, or so it seems.''