The sorting order is determined by the book's metadata. If the metadata puts the author's name in the wrong order (which is often very common on auto-converted books such as from Smashwords), then fixing the metadata will fix the display on the Kindle.
If you have a Windows computer, the easiest way to do it without changing anything else about the file is to use
Mobi2Mobi GUI and be sure to set the names as LASTNAME, FIRSTNAME and LASTNAME, FIRSTNAME & CO-LASTNAME, CO-FIRSTNAME when entering.
Mac and Linux users can still use the command-line version of
Mobi2Mobi, but you need to be technically comfortable with your computer to set it up (or know someone who's willing to try installing it for you).
Hope this helps, and welcome to MobileRead!