Can't full-screen RDP session window?

Hi, I'm using Win7 to RDP to an AWS WinServer2012 box. I need to view RDP session full screen. Checked RDP -> Display configuration, which is set to Full Screen. My machine's resolution is set to 1680x1050.

I checked the Screen Resolution on the server and see "The display settings can't be changed from a remote session." Also, resolution shows a greyed-out 1280x705, under which is a ! Your resolution is lower than 1024 x 768. Some items might not fit and apps might not open.

Any leads?

Thanks,

Scott