so in my server settings, I have it set to always on, and that works just fine for my phones, iPad, etc., but on any Android TV device (a couple of Fire sticks, Chromecast with Google TV…) I have to turn them on manually for every episode of a show.
The language preferences for audio and subtitles are part of your account settings. They’re not specific to your server or a client.
Are you signed into the Android TV devices using the same account?