Hi

Firefox Sync is not designed as a backup service, but to sync bookmarks and other data such as passwords between copies of Firefox.

If you have changed your sync password, you will have lost anything that was being synced between copies of Firefox. If you have your data on another copy of Firefox or have backed up your Firefox profile, you will be able to recover your data.

if you are talking about sync;

Resetting the sync password, or changing its e-mail will remove all data from the servers. The username and password are used to create the encryption.

This is a security feature. https://support.mozilla.org/en-US/kb/ive-lost-my-firefox-sync-account-information

• I've lost my Firefox Sync account information - What to do
• I’ve forgotten, or don't have access to, my Firefox Account email address

Note: Only the data on the servers is cleared. The profile data is not changed or removed.

In the event that the passwords information is lost, you should record all information in a separate text file somewhere else on your hard drive, or written down. You can easily copy and paste if you need to do so. If you are concerned about someone else looking at that file, you can compress it using a password.