In a recent update or the latest version in both Mac and Windows , the viewer screen ( basically what is to be projected ) gets fixated on a single display randomly and basically immovable to another displays after that.
Even the OS shortcut is unable to move that screen to another display. The Main App is however freely movable to any screen, I had seen this issue on a 3 screen setup. even the resize triggers a full screen and doesn't allow drag drop.