Tech Tips - All about Displays
Windows 10 provides an easy way to access and switch between external displays, so you can use more than one monitor or a projector for presentations.
Just hit the "Windows key" + P combination opens this handy toolbar with easy to access options:
Computer only is the default option and the name says it all. Duplicate clones your screen to a connected secondary display, monitor or projector. Extend expands the desktop so you can make room for extra windows. Projector only turns off your laptop's LCD and turns the projector into your monitor.