In “My Books”, when you are viewing the Authors list, there should be a little bubble above the list of authors, which will let you sort the authors themselves by last name, first name, “recent”, as well as number of books. Within the list of books for each author, you can likewise sort by: recent, date added, title, author,
series, file size, and file type.
However, I think when sorting by series the books will always be sorted in series order, i.e. by ascending index within each series. Because each book's number within its series is unique (at least in most of the series I've seen – but I acknowledge series numbering can get messy), there are no ties and so e.g. “The Voyage of the Dawn Treader” (Narnia book 3) would sort before “The Last Battle” (Narnia book 7) despite the latter coming first lexicographically.
Note that if you are sideloading books using Calibre, the series metadata needs a little extra work to load properly. By default, the Kobo does not process Series metadata for sideloaded books when it imports them to its device database. So, after you send a book from Calibre to the Kobo, you must disconnect the Kobo and allow it to import new content, then reconnect it to Calibre and synchronize metadata again.
Only once the Kobo has imported the new content can Calibre set the Series metadata for it. You can use NickelSeries to eliminate this need:
https://www.mobileread.com/forums/sh...d.php?t=331680