Found it. It turned out its easier than I thought. Just monitor display setting, set it to be primary and thats all. How smart I am . Well, on my defence I tried that first and it didn't work. I went online and saw tons of posts on extending / running DCS on multiple screens, creating new lua config files... bla bla bla... which turned something different. That got me so confused!
Anyways, its a learning process!