Hi, always have a current copy of your Profile and your Bookmarks just in case.

• https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles
• https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer

This all I have on Sync :

• https://support.mozilla.org/en-US/kb/how-do-i-set-sync-my-computer
• https://support.mozilla.org/en-US/products/firefox/sync
• https://support.mozilla.org/en-US/kb/how-do-i-choose-what-types-information-sync-firefox
• https://support.mozilla.org/en-US/kb/firefox-sync-troubleshooting-and-tips
• https://support.mozilla.org/en-US/kb/change-primary-email-address-firefox-accounts

Please let us know if this solved your issue or if need further assistance.

The Firefox Accounts vs Firefox Sync is confusing.

I never had a "Firefox Sync" account only a "Firefox Accounts" account, does this information apply?

I have copies of my Profile and Bookmarks, but am uncertain how having copies will help me resolve this.

Hi, Copies will help if forget your password, your email address, change your email address, change password and various other things like delete your profile then it syncs and deletes all the other profiles or bookmarks. There are a ton of reasons I have seen. If you are trying to Sync bookmarks and Profiles then you need a Sync Account I think though this says you can access that in the Firefox Account: https://support.mozilla.org/en-US/kb/access-mozilla-services-firefox-accounts This says you have to create a Sync Account : https://support.mozilla.org/en-US/kb/how-do-i-set-sync-my-computer

Please let us know if this solved your issue or if need further assistance.

Are you using a master password on all devices?

• https://support.mozilla.org/en-US/kb/use-master-password-protect-stored-logins