Every so often my settings change to the default blue and I go back in and manually change it to dark mode and save and it works for a few days until it magically changes without me touching the settings.

Do you delete your browsing history? I believe people have said this causes the settings to reset.

Happens to me once in awhile too, without clearing browser history or cache or anything. Not sure why.

This has never once happened to me ever. I just hope you find out what's causing that to happen. very interesting.

If you clear your Cache and or Browser History this will happen all the time.

This will also happen if you have your Cache being cleared automatically on your browser settings.

I am not manually clearing but I'm going to check and see if it's automatically clearing without me realizing