Q-See QSW8209 - Manual (Page 10)

3. Set the channel of the receiver to the same channel as the camera by pressing
the channel button continuously, the pictures will display on the screen when the
channels match.
Note
： ： ： ：
For clearer pictures you can connect the receiver to a monitor/TV with the
included AV cable (yellow for video and red for audio).
4-2-1. Operation of the Receiver
1. Volume adjustment