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.
this solution is for the problem in which prefresence of toolbar are not saved but in my case the coustomization menu not opens after clicking on customize
see the image attached
Is i should try this solution?
I have solved the problem
i disable the addons which i install just before the problem starts one by one and check which cause problem so i found after disabling e cleaner add on problem solves
and for check again i enable all addons again one by one and now problem not comes again
the addons which i disabled and then enable one by one are:
1.app button remove
3.file and folder shortcuts
but problem not solve
and then i disable e cleaner add on and problem got solve.