I tried SubZero, Bazarr, and just OpenSubtitles connexion but it’s very random… I get good subtitles for some movies/series, but for example, John Wick chapter 1 can’t get good subtitles, I tried the 10 first proposed by the search function…
Oh and they always go back to the native subtitles included when I press pause/play
Which device are you using plex client on? A good way to rule out client issues and server issues is to temporarily try different plex client devices such as plex on web browser or download plex for windows and try it that way and see if subs behave the same way.
I’ve found i got best subs with sub zero but you need to link it to opensubtitles.org with an account you can create on it for free. Try that.