New NVR HELP!!

[Mars Bar]

Hi all i bought a new NVR but its not displaying cameras in full screen. It has this weird middle of screen image.
My old NVR covered the whole screen.
I've looked at setting but can't find anything.
Please help!
I've attached photo of the screen image

 

[CCTVCam]

Substream only?

 

[Griswalduk]

Looks like you have selected the option to live view 8 cameras on the screen but you only have 7 cameras installed. The main large video feed is showing the unused channel

On the dahua line of NVR,s if you double click on one of the smaller live view cameras it will move to the large area and the black unused channel will take its place in the smaller video pictures around the edge of the screen.