Probably, the reason you have connected another display device to your laptop, and you need to have them display different information, how do you get the juice out of it? Press Alt+Tab and hold them while you move between open windows using the arrows on different display screens.
How do I switch between laptop and external monitor?
Another way to switch between these modes is to look for a function key on the top row of keys on your laptop which shows two monitors. Press the Fn key and that function key and it should toggle through the various configurations: laptop display only, laptop + external screen, external screen only.
Can I use my laptop screen and a monitor at the same time?
Most laptops also come with ports that allow you to hook up an external monitor. Plug a monitor into your laptop’s DisplayPort, DVI, or HDMI port and Windows will allow you to use both your laptop’s integrated display and the external monitor at once (see the instructions in the next section).
How do I toggle between screens?
Press “Alt-Tab” to quickly toggle between the current and last viewed window. Repeatedly press the shortcut to select another tab; when you release the keys, Windows displays the selected window.