Projects and books
A project can hold one book or twenty. Characters, locations, magic systems and everything else in World belong to the project, not to a single book, so a series shares one set of records instead of duplicating them.
Adding a book
Open Manuscript and use the book selector at the top, or go to Project settings → Books. New books are numbered in reading order, and the folder on disk is named to match, so your file manager shows them in the right order.
Renaming
Nothing is stuck with the name you gave it first. Rename a project or a book from the Project menu, or by right-clicking a project or a book on the Home page. Mind maps have a rename button beside the one that makes them, and anything in the manuscript list is renamed with F2 or by right-clicking it.
Renaming a project or a book renames its folder too. The internal identifiers do not change, so nothing that referred to it is broken.
Deleting
There is no permanent delete in QuillArk. Removing a project moves it to the _Trash folder inside your Books folder, with a note recording where it came from. Nothing is destroyed, and you can put it back.