Hello,
Lately scammers have been posting   (mainly in threads where no reply has been posted yet),   claiming to be Mozilla experts and asking users to either call a so-called toll-free phone number or giving them a link to a site, where they are promised to get expert help.
These posts of course are scams.
Hopefully informing you about this will scare them off and you won't see such scam post.

Are you getting any error which bookmarking a website? All your bookmarks, history, sessions are saved in firefox profile.

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

Download firefox latest version and install it, it will update the older version.

As I said at the start, it is stuck on 76.0.1, and although it will download an update, and "states restart to update", it will not update. This is not the most annoying thing; the fact that it has lost all bookmarks, and will not accept a copy of an older profile, as the Firefox stated when it updated "this program has a new profile, and will not accept an older version" (or something similar). What is the point of changing the program structure,which is then NOT compatable with the older version, without informing the user of the fact before this is done!

AS I have had no support, all 5 of our computers are now using Waterfox - a browser based on Firefox, but one that will accept all our old bookmarks etc from Firefox with no problems at all. Unfortunately, this means that the support given over the last 20 years, appears now not to have been worth it.

Long live WATERFOX, a browser that WORKS.