Windows Remote Desktop window is smaller than the resolution on the remote system

Question

I'm using windows remote desktop to access multiple host systems. However, the RDP window always pop-up with a HD(1280*720) resolution size even though some connection's display resolution is 1920*1080. Therefore, I had to mannually drag the edge of the window to adapt the remote system's desktop resolution.

How can I set the remote desktop to adapt the remote system's resolution?

this is what I get every time I start a remote desktop connection.