Switching Prosim displays with OC DU module

[mswift]

Hello
I have now assembled my monitor screens in each of the 3 MIP panels and tested the individually panels with Prosim and FSX, everything works great.
I am now wanting to run all 3 panels from my GTX980 GPU's 4 displayport outputs to the monitors VGA inputs.
I started with the CO panel and central panel which I had to rotate to portrait to suit the monitor screen orientation.
I can't drag the Prosim display panel from the primary monitor to monitor 2 (they are in extended mode).
That's my first problem.
Next I want to switch the displays in each panel using the Opencockpits DU module, how is this done? I can't find any reference to how to do this on the Prosim forum, user manual or on the Internet in general.
Can anybody help?
I feel I am so close and it must have been done by many before me but blowed if I can find any mention of how to do it, so frustrating.
Hope it's not another senior moment and something really obvious that I have overlooked.
I have attached some photos of the panels with Prosim displays during testing.
Regards
Mike