As I said, it's a limitation with the OS. It's a bit like wanting to change what monitor your cockpit is displayed on while flying....you can't. The WW MFD's are just USB3 monitors you setup in windows as external displays. You then tell Simappro what to display on each monitor prior to starting DCS.
About the only thing I can suggest is that you purchase 2 x MFD's. One display to switch between the left or right MFD and one purely for the AMPCD