Does this help?

Customize Firefox controls, buttons and toolbars

Type about:customizing<enter> in the address bar.

Note: about:customizing is no longer present in Firefox 47+ releases.

• Press Alt or F10 to bring up the toolbar.
  Then View > Toolbars > Customize.
• Right-click on a blank spot in the toolbar and
  select Customize.

In the new window, look for the icon. When you find it, hold down the left button on it, and move it to where you want it to be. You can move any of the icons you want from here, but; some icons are locked in place.

There is also a Restore Defaults button at the bottom middle.

Thanks Fred, but no. None of the addons are listed in the 'customise' window.

It’s possible that there is a problem with the file(s) that store the extensions registry.

Type about:support in the address bar and press enter.

Under the page logo on the left side, you will see Application Basics. Under this find Profile Folder. To its right press the button Show Folder. This will open your file browser to the current Firefox profile. Now Close Firefox.

Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder

Linux: Under the page logo on the left side, you will see Application Basics. Under this find Profile Directory. To its right press the button Open Directory.

Delete all extensions* files and compatibility.ini in the Firefox profile folder to reset the extensions registry.

• https://support.mozilla.org/kb/Profiles

New files will be created when required.

After, restart Firefox.

See "Corrupt extension files":

• http://kb.mozillazine.org/Unable_to_install_themes_or_extensions

• https://support.mozilla.org/kb/Unable+to+install+add-ons

+++++++++++++++++++++++++++ You will have to approve the updating one last time.

Thank you for that suggestion. Another update became available, so I installed it and re-enabled all the extensions. So far it looks as though all is again as it should be.

That was very good work. Well done. Please flag your last post as Solved Problem so others will know.

I have Firefox 68.01.. I have figured out what keeps disabling my addons... OK from the start.

• I have used the about:config to refresh my Firefox
• Installed addon (adblock plus) works as intended..

UNTIL....

I goto my privacy and security and set my history to to never remember.. FIrefox then Immediately disables my addons... then I have to redo the above steps and stuck with firefox piling up data on my history.. I cant make any changes to it otherwise Firefox fully disables the addon..

Please FIX!

https://addons.mozilla.org/en-US/firefox/addon/expire-history-by-days Expire history by days by Mak Allows to expire history older than a fixed amount of days.