Settings shouldn't get changed as a result of a Firefox update.

Can you provide some examples of settings that did get changed? Did you receive a suggestion to "refresh" Firefox after or during an update?

I found these bug reports;

https://bugzilla.mozilla.org/show_bug.cgi?id=1031347 Firefox Full Installer Changes User Settings

https://bugzilla.mozilla.org/show_bug.cgi?id=1158389 Firefox 37.0.2 update drops all set preferences every time the browser is refreshed in favor of default settings

alphaa100 said

It is beyond annoying when a Firefox or Thunderbird update wipes out existing settings. We update on the idea Mozilla is "dedicated to you, your privacy and an open web" and wants to keep our security intact. And that is wonderful. But please pay attention to the settings we have in place, so we do not trash our existing setup each time we update.

the-edmeister said

Settings shouldn't get changed as a result of a Firefox update. Can you provide some examples of settings that did get changed? Did you receive a suggestion to "refresh" Firefox after or during an update?

the-edmeister, my issue was "losing" my menu. Yes, the same menu that once was not a disappearing but reliable item of my setup. Without further reflection, I presumed the disappearance was due to a recent Firefox update. ("With, therefore, because of" type thinking).

When poster FredMcD responded, he found some reports of lost settings after running Firefox in safe mode that reminded me I had turned off all my AddOns (extensions and plug-ins) in an effort to trace a Firefox memory leak. In booting into safe mode, I may have tripped the setting for menu display into a default for "hidden".