I don't know if you can prevent the change from being made, but you could
automatically return it to a pre-set value with a Change Event macro, like
Before Close, or Before Save..........include this line of code:
ThisWorkbook.BuiltinDocumentProperties("Author").Value = "OriginalAuthorName"
Of course replacing the text OriginiaAuthorName with the name of the
Author you choose.....
But remember, if macros are disabled, this won't work.....
Vaya con Dios,
Chuck, CABGx3