https://support.mozilla.org/en-US/kb/how-to-fix-preferences-wont-save

Note: Some software, like Advanced SystemCare with Surfing Protection, can protect files in the Firefox profile folder against changes. If you have such software then check the settings or uninstall this software.

I don't have any of those installed. It only happened after updating last night. I have always been able to change things up until now.

Also I don't seem to have a "user.js" file and when deleting the "prefs.js" upon recreating it it returned back to the issue. This has really gotten me stumped.

Use these links to create a new profile. Use this new profile as is. Is the problem still there?

http://kb.mozillazine.org/Profile_folder_-_Firefox#Navigating_to_the_profile_folder

https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles

https://support.mozilla.org/en-US/kb/how-run-firefox-when-profile-missing-inaccessible

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

FredMcD said

Use these links to create a new profile. Use this new profile as is. Is the problem still there? http://kb.mozillazine.org/Profile_folder_-_Firefox#Navigating_to_the_profile_folder https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles https://support.mozilla.org/en-US/kb/how-run-firefox-when-profile-missing-inaccessible Type about:profiles<enter> in the address bar.

Sadly its still here.

Edit: Strangely it keeps going away then returning. I refreshed firefox again just to give it a shot and still, after reinstalling it completely (removed it and all files/folders left behind then ran ccleaner) the problem still persists.

Let’s do a full clean re-install; Download Firefox For All languages And Systems {web link} Save the file. Then Close Firefox.

Using your file browser, open the Programs Folder on your computer.

Windows: C:\Program Files C:\Program Files (x86)

Mac: Open the "Applications" folder.
https://support.mozilla.org/en-US/kb/how-download-and-install-firefox-mac

Linux: Check your user manual. If you installed Firefox with the distro-based package manager, you should use the same way to uninstall it - see Install Firefox on Linux. If you downloaded and installed the binary package from the Firefox download page, simply remove the folder Firefox in your home directory.

Do Not remove the profiles folder.

Look for, and rename any Mozilla or Firefox program folders by adding .old to them. Do not rename the Mozilla Thunderbird folder if there is one.

After rebooting the computer, run a registry scanner if you have one. Then run the installer. If all goes well, remove the OLD folders when you are done.

If there is a problem, start your Computer in safe mode and try again.

Starting The Computer In Safe Mode;
Free Online Encyclopedia

Ok it still remains present but this time it didn't happen right away it only occurred after a few minutes. So I went to about:config and looked under taskbar and it says user defined again BUT its a new value this time (see pic).

I'm not worried about loosing anything in my settings and/or bookmarks I use sync. Also it doesn't seem to effect any of my other computers only this one.

If you have sync, and there is a problem anywhere, Shut Down Sync Immediately On All Devices to prevent the problem from spreading. Once the problem is fixed, perform the same repair on all computers before using sync again.

FredMcD said

If you have sync, and there is a problem anywhere, Shut Down Sync Immediately On All Devices to prevent the problem from spreading. Once the problem is fixed, perform the same repair on all computers before using sync again.

I didn't think it this kind of issue would spread through sync.

Sync may be changing your settings. Please disable it.

FredMcD said

Sync may be changing your settings. Please disable it.

I did and its still the same...

Sooooo the problem seems to be resolved, I updated my GPU drivers and I noticed that the right click options where back. Not sure if that had anything to do with it but it seems resolved for now. I'll post here if it happens again.

Good luck. If this works,

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