Thank-you for contacting Slingbox Forum. I am sorry that you are not able to increase the screen size when viewing Slingbox.
I have a few questions. Are you going to slingbox.com and choosing Watch to view programing on the Slingbox? If you are, then are you looking in the upper right corner and see a fullscreen option? If you click on this, it should bring the screen to full size. To reduce it, you will need to click on the picture.
Hope this helps you with this issue!
Have a great day!
Sling Moderation Team