In order to fix a problem I was having with a Firefox add on, I was advised to uninstall and reinstall Firefox. I backed up my Profile folder first and then did the uninstall/install. I then reinstalled the add-on that had been having a problem. The good news is that my problem was resolved. The bad news was that I needed to restore as much of my old configuration setup and things like history and bookmarks. The latter item was fairly simple, I just had to copy places.sqlite from my old profile folder to the new profile folder. Then I reinstalled the other add-ons which had been installed on my previous config. So far so good. The next task, which was probably the most complex and possibly troublesome was to actually restore all of the changes that had been made by me and Firefox itself to the actual config options. Although I didn't keep track over the years, I had made dozens of config changes to fix problems or to get Firefox to work the way I wanted it to. These changes were all made after searching on sites like this, so they were not done capriciously. So I wanted to restore these changes. I copied the prefs.js file from my old profile into the new profile. The only problem I noticed was the that the icons for all the add-ons disappeared from the area to the right of the address bar and search bar. I don't know what this area is called, but it also includes the 'hamburger" icon to open the Firefox menu.

Can anyone tell me which config option this is, or is it controlled by something else?