Currently it doesnt seem possible to highlight more than one channel and in one operation set all of them to a common MIDI channel or port.
Adding this feature would speed up workflow
In fact a collection of tools to manage multiple selection of channels would be very useful.
For example:
1 - assigning a sequentially increasing range of contiguous MIDI channel numbers to a selection
2 - reassignign a sequence starting from 1 -
3 - DELETE - with reassignment channel option - where a gap in MIDI channel range gets filled in so numbers are still contiguous after one has been deleted.