The screen brightness is attached to the same dial as the rest of the dash lights.
The confusion over it sounding like it doesn't dim comes from people (including me) not realizing that the vehicle comes with the dash/display locked to full brightness from the dealer. When in that position, it doesn't dim with the headlights on as you expect. It took me a couple of days to figure out why the screen was so blinding at night.
In the setting menu you can also set the background from white to dark which helps, I believe there are other adjustments in the settings menu that may also help with the brightness.