Hikvision video is grainy at night

Hello, I am wanting to know how to fix my Hikvision camera. At night the footage is grainy, with dots all over the screen but during the day the image is perfectly fine. I have read other things from different websites, they have said to try changing the "gain" setting, and other video settings.

What exactly am i suppose to change, and my gain settings is faded and doesnt allow me to change it. What is the reason for this gain setting and how can i enable it. currently it is stuck at a...

Hikvision video is grainy at night