Hi, this is related to the GPU’s capabilities.
Please consult this article from our online knowledge base:
How to solve ‘stuck resolution’ problems on headless machines
https://kb.nomachine.com/AR05S01127
“In some cases users can get only a small screen resolution without the possibility to change it (‘stuck resolution’). This depends on the GPU which makes available only one resolution when the monitor is not present.
A common solution is to adopt a fake display dongle (also called ‘dummy dongle’) inserted in the video card port to simulate the presence of a screen and force the system to take full advantage of the GPU as if a real monitor is connected.”
I’m not sure what you mean by “Opening the settings on the headless windows machine also doesn’t really work because when I scroll to the desired setting only the scrollbar moves and everything else stays still.” A recording of the NoMachine session would be useful to illustrate the problem perhaps.