Multi Screen Problem in full screen

Before I start, I'll give you some history.

Ive always been able to manage to run 3 screens on my graphics card - nvidia gtx970 My main 27" is via a dvi port and 2 others via a vga to displayport adapter. All worked fine in full screen. I had built a very crude 737 sst and used the 2 smaller screens to display the pfd/nd and eicas.

Fast so forward a few months to last week. I took delivery of a simworld sst and once finished, hooked up 2 new lower monitors (nothing special) but one slightly wider and one that I rotated the screen the portrait and hooked everything up.

In windows, all 3 screens are recognised. No problem.

As as soon as I launch a flight in FSX, the main screen loads and is fine, but the 2 lower screens stay in windows mode and won't go black, leaving me unable to move the displays into the screens.

What at am I missing? What do I need to do to get the 2 lower screens to be recognised in fsx!

Please help!!!

dan