Thanks. I found the single button set for a single notebook and that was useful. I have not found a global single button set though. For global settings all I found was the stylesheet settings which looks like it would take hours to set up.
You can set it globally in the interface settings. In the toolbar there is a button to set the dark or light mode for the single notebook.
So, I'm not finding anything anywhere called "interface".
Linux and Windows: Edit > Preferences > Interface
Mac: Application Menu > Settings... > Interface
Thanks.
