This is on p.37 of the Nav. manual:
Changing between day mode and night model. Depending on the position of the headlight switch, the screen changes to day mode or night mode.
To display the screen in day mode even with the headlight switch on, select
“Day Mode” on the adjustment screen for brightness and contrast control.
If the screen is set in day mode with the headlight switch turned on, this condition is memorized in the system even with the
hybrid system turned off. If the instrument panel light control switch
is turned fully to upper, the displays condition is not changed to night mode
even if headlight switch is turned on.