How do you completely turn off update checks in Firefox v64?
You can use a policies.json file to disable updates for all users.
https://github.com/mozilla/policy-templates/blob/master/README.md
or
https://winaero.com/blog/disable-updates-firefox-63-above/

Look on your desktop. Do you see a folder called; Old Firefox? Look inside. Look for the folder with the latest creation date.

https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile

https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles

https://support.mozilla.org/en-US/kb/how-run-firefox-when-profile-missing-inaccessible

Hi wildchild1954, did you ever set a Master Password to protect your locally stored logins? If not, don't do that right now, we need to do a little data recovery first.

Firefox uses a pair of files that work in coordination with one another, and this has changed at various times, which makes downgrading very complicated.

Please immediately back up these files from your profile folder to a convenient location (see: Profiles - Where Firefox stores your bookmarks, passwords and other user data):

• logins.json
• key3.db
• key4.db

Older versions of Firefox used key3.db to encrypt the passwords in logins.json; newer versions use key4.db. However, the other data (site, username) in logins.json usually are readable even if passwords can't be read. To see what is in logins.json, you could open it in Firefox (for example, by drag-and-drop into an open page). Does it show the missing logins are still in the file, even if Firefox can't currently extract them?

Speaking of profiles, you could take a look at the internal about:profiles page to see whether the Firefox 72 updater created a fresh profile and you have an older one just sitting there. IMPORTANT: Do not delete profiles on this page without making backups of all valuable data.

What are the most important reason s to keep using that Firefox 55 version because that isn't safe ?

• https://support.mozilla.org/en-US/kb/update-firefox-latest-version
• Help -> About Firefox

It is possible that you updated to a newer Firefox version that used a stronger encryption for the passwords and that logins.json is no longer compatible with Firefox 55.

You can check in Windows Explorer if there is a previous version of logins.json and possibly key3.db available from before the update.

• right-click: Properties -> Previous Versions
• https://support.microsoft.com/en-us/help/17119/windows-7-recover-lost-delete-files