Cannot switch between monitors

[stingray]

Hi,
I have ver 1.2.4 on Windows 10 PCs - both viewer and server.

When I click on the icon at the top of the screen, it does not switch to other screens.

Server: 2 monitors
Viewer: 2 monitors, but only need 1 monitor for uVNC.

I think I read that it was fixed on 1.2.2 for windows 10 or something, but I still cannot do it.
Is the latest version capable of this?
In the property window, I see "desktop duplication." Is this it?

Thank you for your help.