In MDL-78426, where the theme selector is renamed and given some additional functionality, the hierarchy was simplified (removing the Theme category), with the intention that the next related item to be renamed/revisited would be "Theme settings".

The scope of this issue is:

1. Revisit the contents of that page, as some items make sense to keep together and specifically relate to theme usage, but others are UI related but do not seem theme specific. I would propose that we move all settings that are listed below "Allow theme changes in the URL" on the page, to more appropriate locations (so from "Allow users to hide blocks " onwards).
2. Determine a more appropriate name for that page, which better reflects what is available from there - it contains theme related configuration options, not settings within themes. I think it makes sense to discuss and decide on this after any changes from #1 have been decided, because the scope/purpose of the page will be clearer so we can rename more effectively.