When this issue occurs, you can only see text in two pages in whiteboard in Microsoft Lync 2013.
Note You cannot scroll down the text by using either a keyboard or a mouse scroll button.
Cause
This issue occurs because the whiteboard size is restricted to two pages in Lync 2013. Although you can paste text that extends beyond the viewable whiteboard canvas, Lync 2013 does not support scrolling inindividual annotations.
Resolution
To resolve this issue, install the March 10, 2015 update for Lync 2013.
Note After you apply this update, you will be able to scroll in a text box by using the "Arrow" keys.
