The intensity of the keyboard backlight and the conditions under which this backlight is activated can be configured by opening the Keyboard Light settings.
Go to
Settings
.
Touch
Display
Advanced
Keyboard backlight
.
Touch Keyboard light level. A slider appears.
Adjust the light level by sliding the icon. Change level by 10% increments.
Touch
Keyboard light timeout
. The Keyboard light timeout dialog appears
Select the amount of time that the backlight stays on before turning off: