This is a “work in progress” that still has a few rough edges, but I am working my way through finding and fixing them as we speak.
Please have a look at:
Which might answer your current query with how subtitle styles work, and follow up on that thread with any other issues you have, or things you would like to see different with this.
I’ve already fixed quite a few of them, but there’s a bit more still to be done before that’s ready to be pushed out for wider user testing.