Subtitle language keeps changing for YouTube

How to ?
1

I set “YouTube subtitle language” as “Chinese (Simplified)” and translation to “English”: https://i.imgur.com/c9mqfZr.png

However, depending on the video, the language (“YouTube subtitle language”) keeps changing to anything, like “English >> Vietnamese”, “English >> Korean”, “English >> Portuguese”, “Vietnamese (auto-generated)” or other options… I’m not sure what “>>” or “(auto-generated)” means here, but:

  1. In such cases (the ones with “>>”), English is shown on the list as well - why isn’t it used?
  2. Sometimes it seems to be happening even if Chinese is available: https://i.imgur.com/g9rPDNc.png

Is it not possible to globally set a LIST of preferred languages (e.g. “Chinese (Simplified)”, “Chinese (Taiwan)”, [any other varieties], “English”) and only show something else if nothing from my list is available?