
Microsoft Lumia 640
Set display brightness
Slide your finger down the display starting from the top edge of your phone.
Press ALL SETTINGS.
Press ALL SETTINGS.
Press brightness.
Press the indicator next to "Automatically adjust" to turn the function on or off.
If you turn off the function:
Press the field below "Level".
Press the field below "Level".
Press the required setting.
Return to the home screen
Press the home icon to return to the home screen.