To select different display settings at any time, open Display Settings in Control Panel.
Open Display Settings by clicking the Start button , clicking Control Panel, clicking Appearance and Personalization, clicking Personalization, and then clicking Display Settings.
Choose the appearance of additional displays
After you connect an additional monitor, you can use the New Display Detected dialog box to indicate how you want you’re desktop to appear on the monitor's display.
You can choose to mirror, or duplicate, your desktop on all displays. A mirrored desktop—the default display option—is useful if you plan to use your mobile PC to give a presentation on a projector or a fixed display in a conference room, such as a wallmounted plasma display or TVtype monitor.When you want to increase your desktop area, you can extend your desktop across all displays, so that you can move program windows back
and forth between the different displays. For example, you can use Microsoft Office OneNote to take notes on your mobile PC while presenting information to colleagues on an external display that everyone can see.
You can also show your desktop only on the external display. This option is useful when you play a DVD on a mobile PC that supports fullscreen video playback on a single display. You can also save battery power by turning off the mobile PC display and using only the external display.