in case anyone is still having problems with having a bold font appearing everywhere after restart that is not fixed by reseting themes here is what I've come up with.
After an hour of ripping my hair out I finally narrowed it down to a very simple thing
"C:\Windows\Fonts" folder was missing the default windows font - Tahoma (C:\Windows\Fonts\Tahoma)
I have no idea how it got deleted but it has without my consent. All I had was Tahoma Bold that was probably being used instead.
Anyways I've downloaded and reinstalled this font you can google it. I've got it from Download tahoma.ttf | Fontonic | Designers Resources
Hope this helps and damn you windows for wasting so much of my time.