A folio is a collection of set lists, the way a book is a collection of songs. Use folios for different types of set lists, such as different venues, bands, wedding setlists, etc.
A set list can belong to more than one folio. All Sets holds every set list. Unbound Sets holds set lists that are in no folio you created. Both are permanent, and neither has a menu. The count beside a name is how many set lists it holds.
Open the Folios drawer. The back arrow returns to Libraries.
The bottom actopm buttons provide actions for modifying folios. While you are checking set lists to add or remove, the buttons become Cancel, Select..., and Save Changes. Select... offers Select all, Select none, and Invert selection.
Tap a folio to open its set lists. A long press selects it and, unless the folio is permanent, opens its menu.
Adding or removing set lists opens a checklist. Uncheck a set list to take it out, or check one to put it in, then tap Save Changes.