Dimming MFD


How do you Dim the MFD screen without also dimming the control bottons on the right side of the MFD? When I dim the screen at night on my MFD 12 to a comfortable level, I can no longer see the control function keys.
I don't have one to try right now but I think you don't want to DIM the unit. You want to use the dedicated NIGHT mode selection in your settings.
Dimming the screen uses less power. Does night mode also use less power? Equivalent to a very dim screen? Power is always an issue on sailboats and needs to be saved usually.
Just wondering.
If the screen is dimmed down by the Night mode or you adjusting overall BRILL adjustment, the power savings would be the same.