Editing metadata for azw files is problematic. I tried on both mac and windows platforms using mobi2mobi command line and GUI, no joy due to crashes at conversion.
Anyway, if you want the cover, author, title, etc to all stick and work well with the Kindle, here is one way. This also lets you reconstruct the metadata painlessly using online searching. You will need to end up with kindle-compatible .MOBI files instead of .AZW files - but who cares as long as they work great on your Kindle?
1. Download Calibre (its free and open source)
2. Use Calibe to (relatively) automatically reconstruct book title, author, series, book# in series, and Cover image from your files.
3. Save file as a .MOBI in from Calibre (you can use the convert option with output formatted for Kindle, but save as a .MOBI, not .AZW.)
4. Drop the .MOBI files in your kindle's documents directory.
5. Presto! Title, Author, Cover, etc all formatted correctly within the Kindle.
