Recently, we have switched our server that handles Remote Desktop connections from 2003 to 2012. When I run the same winForms program on each server, the one on 2012 appears to be larger. My workstation is Windows 10 and I put the resolution down to 1280 x 768 so I can see the screen at the top and the bottom on each RDP session on each server. On the 2003 server, the screen fits the desktop. On the 2012 server, the screen goes below the desktop and you can't see the bottom. It appears the controls such as the text boxes are just a little larger which is forcing the whole program to be larger.
I did check the "Change the size of text, apps, and other items" on Windows 10 desktop and it's set to 100% (Recommended). This doesn't seem to be the problem.
Does anyone have any ideas why the behavior would change between the two servers?
This is probably because 2012 does DPI-scaling (so the remote session tries to adjust the DPI to the same as it is on the client session): https://superuser.com/questions/830234/remote-desktop-into-windows-8-1-pc-with-high-dpi-scaling (also, I guess that you mean 2012R2 because DPI scaling only appears in RDP 8.1 which corresponds to 2012R2).