Thank you for your suggestion DeAnna! We will put it on our list of additional features to include in PER 2.0. (Right now we're in PER 1.0)
You are correct. Right now while you can always add or delete materials in a Course (in Courses at a Glance) you can't edit existing materials.
Suggestion: Right now one thing you could do, as a work around, is to add the authors by adding one more book item: Type: book Title: The authors of the above books Additional Notes on this Item: (then list all the authors, in order of the above books, that you had already entered.)
This way you wouldn't have to re-enter the book titles. These author names wouldn't be connected on the same line as the book titles, but you would be getting the authors' names into your Materials Report, and it would be clear that the authors match the above books.
If you do that, please let us know how you like it! Thanks so much, Virginia Vagt, Editor at Home School, Inc.