can’t help with the basic problem, but I do know that once you have manually selected a subtitle or audio track, that Plex will remember that selection forever and a day and use it for all devices.
There is no way to reset it to the default… So once you have manually selected anything, you are stuck with that choice (or forced to make another manual selection) no matter what your settings are for audio or subtitles.
I made a feature request a couple of years ago here:
for that problem, but it isn’t too high on the list of priorities for many people.
