My Ff doesn't skin fully either, and hasn't for some time.

I believe its more on Firefox updates, and nothing to do with Windows updates itself. But, I can't tell you when exactly.

Thank you,

Basj,
Stardock Community Assistant

hopefully someone whos fixed this issue can reply... anyone...

Check the thread I have a solution

I don't use Firefox often but I thought that I would give this a try. Your instructions for the second part are not that clear, for example, when I do a right click, I do not see "Change Resource" but I might be doing something wrong.
You should do a video, I think a lot of people would like to know this.

Quoting Gaspershooters,

reply 11

Dude,he literally told you ignored the icon change part unless you using "rinfox" theme.  

OK, I read that but forgot about it when I jumped to the instructions an hour later, I am an old guy, I forget my name sometimes.

Just made a tutorial

https://www.youtube.com/watch?v=tzuaZZF78LQ&feature=youtu.be

There is a easy alternative, if one is open and willing to try another browser other than Mozilla's Firefox. I am using Pale Moon, and it skins very easily, with no needs for extras like Resource Hacker, etc. Pale Moon has some relation to Firefox, and yet is independant enough to be more easily customized in some ways. Just a suggestion or a alternate option to consider. 

Just Firefox skins relatively well, especially all around the browser, but about a year ago it stopped skinning the menus due to something they did with the update around that time. Firefox 78 was ok, the menu's still got skinned, bur from 79 it was gone.  So now it is this boring menu's as in the clip.  But the buttons, max, minimize, close and roll-up all skins.  I installed this skin this morning, Lotus by LightStar.

On another note, sometime recently the website name and such are now showing at the top of the browser, even when not maximized which some time ago was not the case.

So if using Firefox and rinfox together it might be a problem in rinfox side, since just Firefox skins as well at it can be skinned ?  And no I am not a skinner just an avid user of skinned teams !   So have no insight in how to get things to work, just thought I add my thoughts incase it helps somewhat.

Going to check out Pale Moon though since I do miss the skinned menu's !

I spent an hour customizing my Firefox, most of that time was finding a suitable theme and wallpaper. I am quite fond of foxes, I live in the country and have a fox that comes to my door for eggs, she will take an egg from my hand very gently. 

How do you get Pale Moon to match the WB?

I am using Pale Moon, and it skins very easily, with no needs for extras like Resource Hacker, etc.