To fix this problem, you have two options: 
 
  1. Start by going to a Recurring Gift record then clicking Edit Layout in the top right corner. 
  2. Find the Recurring GIft Set Designation widget, hover over it, then click the wrench icon in the top right corner of the widget. 
  3. Now you can either change the Height (400 should work) or you can click on the Show scrollbars checkbox.