The screen brightness of your thermostat is at its maximum level when your are using it. When your thermostat is in standby mode, the screen brightness is, by default, automatically adjusted according to the ambient light. It is possible to change the screen brightness of your thermostat in the Home + Control App : go to settings, select ;Manage my home ;, select the room in which the thermostat is installed, select the thermostat and select ;Advanced ;, then you will be able to put the screen brightness always off or to set a customized level.