[jhowell]

When you use calibre to send books to your Kindle via USB the metadata in those books is updated to match what is currently in your calibre library. The default setting of "use author sort for author" set for MOBI format in Preferences -> Output Options -> MOBI output controls whether Author or Author Sort is used at that time. There is no need to re-convert.

(Note that the setting for MOBI output is used even if the book is in AZW3 format.)

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Kindles sort by whatever is in the author field of the copy of the book on the device, but will unwrap a name containing a comma for display purposes. For example:

"Smith, John" sorts by "S" and displays as "John Smith"

If the author field is instead set to "John Smith" it will sort by "J", but still display as "John Smith".