Lync 2013 doesn't show who changes content on a shared whiteboard in an online meeting

To resolve this issue, install the March 10, 2015 update for Lync 2013.

After you apply this update, users can see who modified the text annotation on the whiteboard. When the user clicks the text annotation, a box is displayed that identifies the person who created and modified that text annotation. Other types of annotations do not display who created or modified the object on the whiteboard.