channels

The "Channels" dialog allows manipulation of the song's channels.

Each channel has the following options:

Visible: uncheck the box to hide the channel from view. Pattern data will be kept.
Crossed-arrows button: Click and drag to rearrange pattern data throughout the song. Note: This does not move channels around within a chip! It only affects pattern data.
Name is the name displayed at the top of each channel in the tracker view.
To the right of that is the abbreviation used above each channel in the order view.