Not sure what program you are using, but just prior to the program which I open ( to a very small screen), there is an "APPLICATIONS" window, at the top right hand corner of the window, there are 3 icons, one is what appears to be a clipboard with 2 red checks. It is to "CUSTOMIZE USER INTERFACE"
Click on this, and you should go to a "settings or index" screen. Click on "CONNECTION PREFERENCE"
Then click on the "FULL SCREEN" setting for window size.
Hope this helps!