There are two possibilities that may cause the Night Hours Protection settings in the Quick Menu to become grayed out:
If the function is (1) set to OFF, or (2) set to Auto Switch and is not activated under a bright environment.
1. If the function is set to OFF, go to Menu > Eye Care > Night Hours Protection
> Switch and set the function to ON.
2. If the function is set to Auto Switch, go to Menu > Eye Care
> Night Hours Protection > Switch and set the function to ON.