Thank you very much for all of this info!
Most of it was known to me already but I also learned about ApplySettings that way.
We also run a Wiki (linked at the top) where this info would make sense to be added at the examples/tutorials section at the top right.
I've added your thread link there:
https://wiki.esoui.com/How_to_change_ingame_settings
As addition there is a GetSettingsBool API function as often settings are just on/off. It eases the toggling as you do not need to change the normally returned string values 1 or 0 manually in your code for your usage like
If settingVar then (compared to if settingVar == "1" then).
I've moved your thread to the tutorials and info forum.
btw:
SetCVar also is used to directly change the client's language (no videos or audio! This needs to be changed in the ESO launcher settings AND downloads several GB then of video and audio files) directly to supported languages like de, en, es (next chapter, not yet on live server!), fr, ru and jp (only special Japanese client!)
Code:
/script SetCVar("language.2", "fr") --Change to French and reload the UI
This will be remembered after logout, so it is written to the UserSettings.xt file, but as you correctly said: The language is not stored at the server.
Settings of the ingame settings menus (except AddOns!) and controls/keybindings are stored at the server (~200 max keybinds per character).
All other settings like addons or even ZOs settings like "Include banked items at crafting table" are stored in the local SavedVariables folder. ZOs settingsa re stored there in ZO_*.lua files.