Dual Monitor Help?

I bought a monitor for multiple reasons and i currently have it set up to my laptop via HDMI. I currently have it set as an extension of my screen in my display properties but when I try to launch a game or put a program into full screen, it will only go full screen on my laptops screen and wont extend to the monitor. How can I play and use programs to span across both screens? Note: Ive tried stretching the programs across both monitors, some work and some wont let me, this means that their in windowed mode as well.