Problem with ChannelType - Can't display all cams + IPcam

I have a typical KKMoon Chinese Ebay 8-channel DVR, 6 normal cameras connected to BNC ports and 1 IPCamera connected over the Local Area Network.

In order to show the digital cam (IPcam), I have to go to my menu-->System--Digital-->ChannelType settings and select a configuration which supports the IPcam.

BUT what I don't understand is WHY I can only have 1 IPcam, and 2 regular cams, or 8 IPcams, 0 regular cams, etc.

Why Can't I display all 6 of my regular cams AND the IPcam? It is an 8 channel DVR, I don't see why I should be limited to 3 displays when I want to view both types of cams.

Anyone know how I can change this?

Thank you.