The channel ordering in Live Cut depends on which channels were selected for the Live Cut project in the first place. For instance, when you have eight channels selected in the just:control user interface, then you will have eight channels in your Live Cut project. Channel ordering goes from top left to bottom right, as can be seen in following screenshot.
In case you have eight channels connected in just:control and you are only using four channels (in this case, Ch1, 2, 5 and 6) for Live Cut, then the channel ordering changes accordingly. Please see screenshots below.
You can still see all connected channels, but only the selected channels can be used for Live Cut. The other four channels (Ch3, 4, 7, 8) are greyed out and can not be used for Live Cut. If you are working with a different set of channels for different scenes and you do want to your CAM4 always stays as CH4 in Live Cut, then you can do that with different Live Cut templates and channel mappings. That means that you will have to create a Live Cut template for each scene. So you will have a Live Cut project for a three camera scene, a five camera scene and so on.