Windows 8;
To change display settings
Open Display Settings by clicking the Start button , clicking Control Panel, clicking Appearance and Personalization, clicking Personalization, and then clicking Display Settings.
To designate the primary display, on the Monitor tab, click the icon that corresponds to the monitor that you want to designate as the primary display, and then select the This is my main monitor check box.
Select the screen resolution and color quality for each monitor that you're using.