Originally Posted by holymadness
Seems like this is a problem with the Kindle app for iOS, and not the device per se.
Mine are sorted by first name on my iPhone, too. I don't see a way to change this unfortunately.
No, the Kindle app on my iPad 3 shows the authors sorted by last name. I never use calibre, just the Amazon cloud. So I'm thinking this is a calibre error.
EDIT: On closer examination the Books are sorting by lastname and the Docs are sorting by firstname. The Books are coming from the Cloud but the Docs are coming from various sources including the Cloud and side loading, but since the Docs are all modified it could be that the author names were incorrectly converted.