When you CTRL+S to save the schematic library, will pop up a dialog, you can choose this library’s owner:

After finish, you can find your library at the left panel: Libraries > SCH Libs > Personal/Team > All


When you select it , right-click it and select the menu “modify”, you can add a tag for it.


When you favorite a library, you can find it at Libraries > SCH Libs > Personal > Favorite​ , If this library has a tag, the tag will show up too, but you can’t edit that.
But you can via “Clone” or “Edit and save” to create a new library to personal libraries.