So I have some ideas on how this should work, we should make it like a settings ring with a timeout, like is super commonly seen on blindness technology (e.g. the Victor Reader).
Volume should be the default. If I just randomly pick up my ccalcvox after not touching it for a bit, the knob should adjust volume.
Press a button to change what it adjusts. For example, pressing it once should start setting pitch, twice voice, etc.
There will be a timer for having the setting reset to volume. Probably after around 5 seconds by default.
Make the toggle between what the knob changes more easy to understand. Allow it to be more expandable