For changing screen brightness in Windows 10 , select Start , choose Settings , then select System > Display . Under Brightness and color, move the Change brightness slider to adjust the brightness. (If the slider isn't there, see the Notes section below.) Some PCs can let Windows automatically adjust screen brightness based on the current lighting conditions. To find out if your PC supports this, in Display settings, under Brightness and color, look for the Change brightness automatically when lighting changes check box, and then select it to use this feature. This automatic setting helps make sure your screen is readable wherever you go. Even if you use it, you can still move the Change brightness slider to fine-tune the brightness level. Notes: You might not see the Change brightness slider on desktop PCs that have an external monito...