When saving a word document all comments become by "Author"

As stated in the subject, it is hugely annoying when you are trying to review papers from multiple people that have been passing along a draft if this happens. You need to :

In Word 2010, go to File->Options->Trust Center->Trust Center Settings. Then, uncheck "Remove personal information from the file properties on save"

In Word 2013, it falls under File -> Options -> Trust Center -> Trust Center Settings... -> Privacy Options. It is found under the Document-specific settings section.

 
Source:  here