Adjust screen brightness on the Kobo Books app for Android

You can make several changes while reading to make your screen easier on your eyes.

Tap the centre of the page to bring up the Reading Menu.
Tap the Brightness icon.
Tap the reading theme you want to use. If you're reading at night, the Night theme is specially designed to make it easier to read by displaying white letters on a black background.
Under Brightness, drag the slider to adjust your screen's brightness level. If you don't see a brightness slider, you may need to enter your Android device's Display settings, and disable Adaptive Brightness.
To save your settings and resume reading, tap X.