The Reset Firefox feature can fix many issues by restoring Firefox to its factory default state while saving your essential information.
Note: This will cause you to lose any Extensions, Open websites, and some Preferences.
To Reset Firefox do the following:
Go to Firefox > Help > Troubleshooting Information.
Click the "Reset Firefox" button.
Firefox will close and reset. After Firefox is done, it will show a window with the information that is imported. Click Finish.
Firefox will open with all factory defaults applied.
Nothing works that I have found to fix this problem. It started with the 19 update and has totally screwed up Firefox. I have searched the forum and all of the suggestions that I can find have been tried. When I start Firefox it always goes to the same goofy Firefox home page, not where I want to go. It always asks if I want to help improve firefox. Too bad but you really messed up with this update.
LIke I said, I've already tried all of that and it simply DOES NOT WORK. All of this started with the 19 update and FF has been simply annoying ever since then. They will perhaps stick for one or two times then everything goes back to a new install/update mode with the same annoying questions (they're annoying the FIRST time they come up - after that they get down right obnoxious). Guess Chrome has just become my new favorite browser.