I'm viewing my iMac 5k screen at a comfortable 2880x1620 res in Sierra 10.12.4 . I often remote in to my non-retina 24" iMac with a native res of 1920x1200. When using the remote screen, it displays at it's native res, even on full-screen mode. I've tried to upscale it beyond that to fill my larger screen but I can't get that to work. Can it be done and if so, how. Thanks.