Users can change the virtual desktop application size from User Experience: 
  1. Log into your datacenter web page
  2. At the top of the page, click Settings
  3. On this page under User Adminstration, click the Window size drop-down box
  4. You can select Seamless (no window boarders), No Preference, fit to screen, Custom, or select a size that more closely matches your monitor or size you wish to set.