It is usually the case that having things done for you automatically is a good thing — it will generally save you time and effort. But that is not always the case; sometimes it is better to be in control. One area that Windows will attempt to take control of is screen brightness. The brightness of your screen can be automatically adjusted according to ambient light levels. The aim is to make things easier for you to see, but it can be distracting if the screen is constantly changing in front of your eyes.
If you would prefer to take manual control of screen brightness levels, it is easy to do so. Press the Windows key and C to call up the Charms bar and then click Settings followed by Control Panel. Open the Power Options applet.
To the right hand side of the window you will see two or more power profiles and one of them will be selected as the active one. Click the Change plans settings link next to the active profile and then click the Change advanced power settings link.
Scroll down to the bottom of the list of options and click the + symbol next to the Display entry. Next, click the + symbol next to the Enable adaptive brightness setting.
You can choose different setting for when you computer is plugged into power and when it is running on battery. This is ideal if you want to maximize your battery life as you can disable adaptive brightness and turn brightness all the way down.
From both the On battery and Plugged in drop down menus, pick On or Off according to your preference.
Click OK and you’re done. You can then manual configure brightness to whatever level you like without having to worry about Windows them changing it for you.