I have a similar problem, how do you change the authorization
If you change the account that your computer is activated with, it does not change the activation that is stored in the books when you purchased the book.
So if you use account A to activate Adobe Digital Editions then purchase a book and open it in Adobe Digital Editions. Then deactivate Adobe Digital Editions and activate with account B, you will not/should not be able to open the book you purchased using account A (unless you join account A to account B but we won't go any further with that).
Had the same issue. On-line chat trying to reset my password resulted in a "new ADE account" as they are unable to provide a reasonable way to reset the password so that you can update the e-mail address.
When you authorize your e-reader with a "new DRM" the e-books are still linked to the "old DRM".
Now the majority of my library is inaccessible as the defunct EMAIL ADDRESS and therefore the "old" DRM code is ATTACHED to the e-book.
Will be happy when ADE goes the way of the dinosaur.
I too "Will be happy when ADE goes the way of the dinosaur". Worst, most inconvenient piece of malware I've seen. I bought a book and a used ereader off ebay. Does adobe DE actually see that reader?? No. Can I read my book? No. Will I find help on the Adobe site? No. It just goes on and on.