This has never happened to me, though I to would be hopping mad as well if it did.

I doubt that Dark Mode even existed when I last used Firefox on Windows but it has never switched itself on on Linux so I wonder if it's WINDOWS that causing the problem rather than Firefox itself; most developers seem to think that users want to feel like they are in a coal-mine.

Under Firefox's Settings under Appearance you can choose "Automatic," "Light" or "Dark." Below that is a box to "Manage Colours" so a fiddle about with either of these may be worth trying.

Those were the first things I tried messing with years ago when this first started being a problem. Sadly they have never done anything.

Nothing has changed with my windows settings for years and only firefox recently updated so I see no reason why that would have any impact on this suddenly becoming an issue again. Checking windows settings again they remain exactly as I have had them for years with no changes and until the last 2 days the about:config settings I had to go in and change saved just fine.

Supposedly if you set it to "Light" it should automatically turn any website with a light and dark mode into light mode without you having to click the toggle yourself? But even that has never actually done anything that I could see and websites aren't the problem it's firefox's menus that I want in light mode.

Note that some websites are by default in dark mode, i.e. they have white text on a dark background.

Can you post a link to a publicly accessible page (i.e. no authentication or signing on required)?

It is NOT websites that are forcing dark mode. It is firefox MENUS despite me changing things (as detailed in first post) so that it shouldn't using:

browser.theme.content-theme set to 1 browser.theme.toolbar-theme set to 1 and previously layout.css.prefers-color-scheme.content-override = 1 (Although this last one appears to have been made unusable)

While these work neither of these saves and force me to manually re enter them in about:config EACH TIME firefox is restarted. And this is all despite me changing to a theme with light mode where there shouldn't be any dark mode menus but firefox is broken and forcing half of them to be dark mode despite this.

OK, try this:—

Open a text editor and paste this into it:— user_pref("browser.theme.content-theme", 1); user_pref("browser.theme.toolbar-theme", 1); Save it as user.js in your Profile folder.

What profile and how do I make a user.js file?

I'm sorry this is starting to go way over my head :( I don't feel like there should be any need for me to go through these hoops to do something that should and has been part of firefox before

My apologies; you seemed to already know your way 'round Firefox and I didn't want to be patronising.

Firstly open Notepad and and enter the text I gave above. Save it as user.js somewhere easy to find, like your Desktop. Make sure it's saved as user.js and not user.js.txt — if it has rename it correctly by highlighting it and pressing F2. If it seems to just be called user right click it and choose Properties to see its full name.

In Firefox go to about:profiles. In the blue column that shows up on the left look down for Default Profile, which may well be the only one. Just under that it says Root Directory. At the right end of that line is a button labelled 'Open Directory.' Click that and it will open your profile folder in Windows Explorer. Drag the user.js file you made into that. Restart Firefox.

You've previously said that you can make the changes in about:config to get rid of the dark theme but they only works until you restart Firefox. The method I'm suggesting will load the same settings every time it starts. If that doesn't work I'm afraid I'm out of ideas.

Yes, I agree that this messing about shouldn't be needed.

I thank you for the consideration and the instructions but beyond following a tutorial I'm afraid I don't know any more about this stuff.

Sadly this is not working. There is another file in the folder Root Directory leads me too that is the same type as the one I made following your instructions (javascript) called prefs that's not one I've put in is that interfering?

If not I guess this will remain unsolved until firefox does something to fix the saving issue :(

My understanding is that prefs.js are the things set by about:config and user.js overrules it.

Hopefully it will get properly fixed in a future release.

So both about:config and the override to it are broken in this version. That sucks

I've been having a play around and the only way I can get Firefox to go dark is to choose a dark theme. The thing under Settings makes the web-page dark but not the the Firefox UI itself.

You said in your initial post that you'd tried other themes so it may be as well to check that something isn't left over from those experiments.

Go to about:addons and see which theme is is enabled. There's one that's built-in called "System theme — auto" which leaves things to the OS, in your case Windows, so if that's the one that's enabled it may explain why your settings aren't sticking. If it is enable the Light one.

I got up-dated to Firefox 129 yesterday so that may improve things for you.

Thank you for looking around to help. I've not used any off the default themes in years (I don't like the light mode and system auto and dark mode have always been right out for me) and have instead been using custom ones found through firefox add on search. Out of nowhere the one I used to have that was giving me white menus with black text changed and I had to go looking for another one.

Despite spending a few hours looking over several that should have given me what I wanted I still get the dark mode menus and I can't find anything that fits what I need for the header and the ui :( And with how there is no way to narrow down the search results I keep having to download->enable->manually check each time it just takes too long to find anything