Is there a way to force unity5 to open up on the operating systems main monitor?

For my app I must make sure the build opens up on Windows 8s / 10s primary monitor always, like it did in older versions of unity (when using 2 or more screens).

Unity lets players choose which monitor to use (which is great, but just not in my case), but by default it seems to just use the left one - even if the right one is the primary.

Sadly, I have found no way to make sure it starts only on the primary screen.

I’m really grateful for any hints, thanks a lot!
Kind regards,
Chris

Are you explicitly setting the targetDisplay=0 property of the camera?