Changing the screen brightness in Windows

Tap or click the network icon on the right side of the taskbar, and then move the brightness slider (with the sun symbol) to adjust the brightness. If you have a connected keyboard, you can also press Windows key + A to open the display.
 

On some PCs, Windows can automatically adjust the screen brightness based on current lighting conditions. 

To find out if your PC supports this, select Settings > System> Screen. Select Brightness, look for the Automatically change brightness as light changes check box, and select it to use this feature. This automatic setting ensures that the screen remains readable in varying light conditions. Even if you use it, you can still move the Brightness slider to optimize the brightness level for a built-in display.