Toyota 2015 Prius Owner's Manual page 282

Day mode
When the headlights are turned on, the screen dims.
However, the screen can be switched to day mode by selecting "Day
Mode".
The screen will stay in day mode when the headlights are turned on until
"Day Mode" is selected again.
PRIUS v_OM_OM47887U_(U)
I n f o r ma t i o n P r o v i d e d b y :
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5-2. Setup
5