Higher Screen Resolution

This works but it makes it HUGE. Way bigger than 1600x1200 it seems. My monitor resolution is set to 1920x1080 and I still have to scroll the VM window to see it all. Changing the "1600x1200" to something else doesn't seem to have any effect. Do you have another way to set it smaller? 1024x768 or even 1280x720 would be perfect. Thanks!

UPDATE: I can change resolutions from 1600x1200 now within the Display Settings - but looks like I need a widescreen and that's not available. I want to place the VM on the secondary monitor which has a max res of 1366x768. At this res, the VM window at 1024x768 is a good width, but just a little off the screen vertically...have to scroll down to get to everything. What I really need is that 720 vertical. Any way to do this? Either 1024x720 or 1280x720?