If the document is a template and already on the user's hard drive, when they double click it to 'open' it, they actually get a New unsaved document which has their username assigned to the Author field. This is achieved without macros and is standard behaviour for Word. You can simply include the Author Content Control in your document to display this (Insert > Quick Parts > Document Property > Author). Then the new document can be saved and the author name for that document won't change without someone choosing to do so.

However, if you are sending the file to them in an email, they are actually opening the template itself so the Author name would remain as per the template.

__________________
Andrew Lockton
Chrysalis Design, Melbourne Australia