More detail than you need-
I never use the channel knobs, and would be happiest if they weren't even there. I do use the recorder for playback, and have it set so that in playback mode those knobs do nothing, adjusting fader level to the mix using the menu knob in the same way as adjusting trim while recording.
The only significance of the channel knobs for me is their control over the stereo-mix while recording. I don't record the stereo mix, so that is only relevant for me in two ways:
1) if I am patching out to someone while recording.
2) when playing back, the initial stereo-mix fader balance carries over from whatever it was set at while recording.
The second is annoying because those knobs end up being set randomly instead of meaningfully. If the fader levels were locked as well during recording this would not be an issue.
As it is I'd rather it revert to a flat zero'ed-out fader balance across all channels prior to the initial playback of the recorded fileset, or a specific saved fader position that doesn't change with each recording. I do like that it automatically saves and recalls fader positions with each subsequent playback however, as that reflects any playback adjustments I make specific to the recording.