You need to remove the tick for the "Use Default" choice to be able to select one of the other choices if you are talking about the "Tools > Page Info > Permissions" window.

If you use extensions (Firefox/Tools > Add-ons > Extensions) that can block content (e.g. Adblock Plus, NoScript, Flash Block, Ghostery) then make sure that such extensions aren't blocking content or settings.

@cor-el, sorry for the delay and thanks for your reply. Your first para pointed to a different controls page than the one t I was grousing about. (My bad for not adding a screen shot - see attached) Although it's a nice page to know about, after looking at all 11 "use defaults" on that page, none seemed to apply to "modifying" the Exceptions popup but I could be mistook. I'm not clear on how an add-on or extension could interfere with just the TOOLS > OPTIONS>PRIVACY>EXCEPTIONS buttons but not all the rest of the many TOOLS > OPTIONS buttons, unless perhaps it's because the apps you mentioned (cookie blockers/trackers) "hook" into the same part of the FF architecture? If so, should somebody on the FF dev team investigate?

Your second para does address the EXCEPTIONS page but only with the standard time-consuming "throw the kitchen sink at it" solution, even more painful than the "trash your customized FF with a reset" solution. It seems that about once a week I have to go through this "weed out all possible conflicts one by one" nonsense for one glitch or another and that really grows tiresome after a decade with increased reliance on add-ons and extensions.

IMHO, the add-ons page itself could stand a user-friendliness upgrade, e.g. 1) add an option to the Add-on page so we can re-sort our whole list by install date rather than alphabetically, allowing us to more easily employ the LIFO method for identifying problem installs. I'm at fault for ending my practice of maintaining a notepad list of when I made a change or added a program about 20 years ago. Even if install date is displayed elsewhere, it'd be so much easier if it was displayed on a sortable add-on list.

2) it'd be nice to have a globally aggregating WHAT'S BLOCKING THIS? option that could create a report log of exactly what blocked what when. That would be worth its weight in gold in saved man hours considering how many users ask for help and get the aforementioned "kitchen sink" solution.

I hate scrolling, not fond of programmers who rely on scroll bars instead of making pop ups resizeable. For example, on the EXCEPTIONS page, is there any good reason why typing a single letter on the input line can't cause the pointer to go TO the domains beginning with that letter, i.e., type G and the scroll bar automatically zips down to G, or type GO and it zips right to GOOGLE? Then again, perhaps it is supposed to function that way and it's being blocked as well?

FWIW, I use most of the blockers you listed and more. To possibly solve just the top 10 glitches I'm experiencing by "making sure such extensions aren't blocking content or settings" could easily consume an entire day of trial and error. Not sure if there exists some sort of aggregate blocking log option but if you know of such a diagnostic tool, add-on, extension, freeware utility, PLEASE let me (and all other stymied FF users) know! Thanks in advance.

Another anomaly I've noticed with that EXCEPTIONS pop up... I customized settings so that everything is supposedly cleared when I close Firefox yet if I set google.com to ALLOW for SESSION and then close FF completely and reopen, google is STILL set to Allow for Session.

Perhaps I misunderstand the concept of "session" but I can't find any glossary definition or apropos Help page when searching HELP for this: exceptions "allow for session"

FF is as bad as Google, providing USELESS fuzzy search results by glomming onto any SINGLE word instead of what I've put in quotes. The above spewed 155 results carved up into some 15 pages (10 per page, impeding a quick scan) that seemed to have nothing to do with my search request. Even worse, FF is highlighting words in the results that I DID NOT search for, words that aren't even derivations of the search words I wanted used, e.g., ACTIVATE and TURN. WTF??

A new session is started if you start Firefox and the current session is ended if you close Firefox. This is different than a Private Browsing mode session in a PB mode window that ends when you close all open PB mode windows.

When there are special permissions set for a domain (i.e. some are not default) then you should see them if you click the "Site Identity Button: (globe/padlock) on the location bar.

Permissions do not change if you close and restart Firefox unless you would clear the "Site Preferences". So the cookies expire and are removed and if you close and restart Firefox then a new session starts and a new set of cookies is created. Only cookies that have an "Allow" exception do not expire and survive the session.