I know there is a way to do this, but I can't remember how. 
 
I would like to quickly solo a track/channel in a group in one click.  For example, if I have a group of five tracks, I would like to be able to click the solo button in one track, and have the other four tracks mute.  Then when I want to be able to quickly solo the second track with one click, without having to un-solo the first track and the solo the new track.  In other words, I would like to just click solo in any of one the tracks and have all of the other tracks in the group mute.
 
Hope this is making sense.

How to group controls http://www.cakewalk.com/Documentation?product=SONAR&language=3&help=Mixing.44.html
 
How to use quick groups http://www.cakewalk.com/Documentation?product=SONAR&language=3&help=Mixing.45.html
 

I'm not entirely shure if this is what your looking for but you could try enabling selective solo in the toolbar (the "<S>" button, below solo)

Sounds like Exclusive Solo is the way to do what you want

I posted this months ago and never thank you all for your help.  Sorry about that.
 
THANK YOU!