How Do You Customize Kodi Xenon (Diggz) Build?

I just got Kodi up and running on a Firestick. I installed the Xenon Build for add-ons. Does anyone have a link to a guide on everything that you can customize and a general use guide?

I’m currently most interested in getting subtitles set up to automatically load. I found a toggle to keep them enabled, but you still have to download the subtitles manually.

Any tips that you might have are also welcome. Even if it’s to recommend a different build, all help is appreciated.