Recently I worked with few support issues where users had documents with Track Changes enabled. When user make the changes in the document, it shows "username" who made the change. But as soon as they hit SAVE button to save the document, username is replace by either "Author" or "A1" etc.
Well the root cause of this issue is option "Remove Personal Information from File Properties on Save" is enabled.
To have your document save the username, uncheck this option. You can find this option under
Office Button|Word Options|Trust Center|Trust Center Settings|Privacy Option|Document Specific Settings
If you have mutiple documents where you want to uncheck this option, you can use following macro sample.
Note:- This Macro is an example to handle specific scenario. You probably need to modify this macro to meet your needs.
WARNING: ANY USE BY YOU OF THE CODE PROVIDED IN THIS EXAMPLE IS AT YOUR OWN RISK. Microsoft provides this macro code "as is" without warranty of any kind, either express or implied, including but not limited to the implied warranties of merchantability and/or fitness for a particular purpose.
If ActiveDocument.RemovePersonalInformation = True Then
ActiveDocument.RemovePersonalInformation = False