– I have the most recent version of Firefox. – I have my settings in Preferences -> Privacy on "Keep third party cookies until I close Firefox". – I've checked "Clear history when Firefox closes" and have ticked every single box under settings (except saved passwords). – But still, Cookies do not get deleted when I close Firefox – there are hundreds of cookies every time I open it. – If I go to Tools -> Clear recent history, choose "everything" and tick every single box, history etc. get deleted but the cookies remain. – If I go to Preferences -> Privacy and click "Show Cookies" and then click "Remove all cookies" twice, the cookies disappear, but they're back just seconds later. – I've even tried going to Preferences, clicking on Exceptions and manually adding some of the websites that showed up under "show cookies" and blocking them and then deleting the cookies, but still they re-appeared within seconds, and the exceptions were blank again. – I've checked all your support pages about this topic. – I've seen this https://support.mozilla.org/en-US/questions/740598?esab=a&as=aaq and tried it and it didn't help. – I've seen this https://support.mozilla.org/en-US/questions/936308?esab=a&as=aaq and this https://support.mozilla.org/en-US/questions/868910?esab=a&as=aaq, and yes I do use "Do Not Track Plus" and some of the Cookies seem to be Opt-Out-Cookies but most are not. Please help me. I used to be a big fan of Firefox but this is getting really scary.