Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of the extensions or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox (Tools) > Add-ons > Appearance/Themes).

• Don't make any changes on the Safe mode start window.
• https://support.mozilla.org/kb/Safe+Mode

• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

See also:

• http://kb.mozillazine.org/Preferences_not_saved
• https://support.mozilla.org/kb/Preferences+are+not+saved

Your problem is probably related to your two opt-out extensions. I recommend you go to their sites to investigate their behavior. I've read of another one that does require "Accept 3rd party cookies" to be kept open.

Disabling your opt-out extensions would enable a quick check.

ZoneAlarm ForceField is also a good candidate for protecting files in the profile folder and thus preventing changes.

thank you for your replies i shall go away and try safe mode and investigate the extensions

I have been having same problem, and until today, couldn't find anyone with the same issue. But I don't understand this response about two opt-out extensions. How do I disable opt-out extensions?

Look at More system details.. to the right of the first posting in this thread to see the listing of installed extensions.

the-edmeister - I'm not sure if you realize that this isn't the original poster.

dnabav1 - you would be better off posting a new question where we can see your system details - refer to question 917566.

Look through your extensions with a name that includes "opt-out" or "taco". The best known one is - Targeted Advertising Cookie Opt-Out (TACO).

You may have an entirely different problem. Don't be too apprehensive about cookies. Anyway, you can always delete them, individually or in a group.

I'll be off the air for a couple of days but others can carry this forward.

Well i have entered firefox in safemode and with all addons disabled and the problem is still there. firefox auto resets to accept 3rd partie cookies on every start even starting in safe mode. Considering firefox is supposedly safe this should not be happening the user should be able to have confidence that options remain set as you want them, I know everybody says 3 party cookie are not a problem but I dont want them !

Hi adrianmac. You are giving up way too early. Have you worked through cor-el's suggestions re preferences not saved? Have you tried disabling Zone Alarm's Force Field?

The very first thing you should do, though, is to go Options>Privacy>check Accept Third Party and set Keep until I close Firefox. Then close Firefox and re-open and go back to Options>Privacy> and have a look at Show Cookies. Are there cookies there? If there are a lot they are probably opt-out cookies. Try to delete them. If they won't delete they are certainly opt-out cookies and they are probably causing your settings(preferences) problem

If there are no cookies you don't have an opt-out problem. As a short-term workaround you could leave the Keep until I close Firefox setting which will delete all cookies or you can manually delete any you wish. And make sure you work through cor-el's suggestions.

Hi thanks for replies I haven't given up yet . The opt out is a google opt permanent opt out of advert cookies Avail on google site .. however i have entered firefox in safemode with all extentions and add ons disabled removed all cookies about 20 or so all deleted.Unset accept 3pc cookies and restarted in safemode again and the box is reticked .I have then uninstalled firefox reinstalled the up to date FF(was on 8 now on ten ) Restarted ff in safe again and the box is ticked unticked and saved restarted tried several times I have had this problem for several months before I installed ghostery this lets me stop the cookies !

When everything is disabled the only thing that stops the cookies installing is setting cookies to "ask me every time " then i can say no to every one which is a pain ! The ghostery addon works but I feel that the ff options should work without having to resort to addons. Hence I though this week I would have another try at solving it.

By the way I have ran malwarebytes, spybot s&d avira All have come up clean

I have the exact same problem, and have done all the steps found in any of the posts here. Please help, I want to be able to disable cookies, but everytime I restart firefox, they are re-enabled.