Assigning Keystation to Output buss

Have a question that is probably newbie. With as much experience as I have with Logic being used for recording and mixing, I haven't done much with it in a live situation. I have a set up for a live performance with two software instrument tracks with a string pad and pizz respectively. I'm playing from a Keystation 49. I'm simply switching tracks by "arrowing" up and down depending on when I need pads or pizz. My issue involves the volume slider. As I move from track to track, the volume control is of course effecting each track. So when I return to a previous track the volume changes or the virtual fader has to "catch up" to the changes I made when playing the previous track.

I'd like the volume slider on my Keystation 49 to instead controll the Output buss volume, and not each individual track. I am guessing I could set up something like this in the Environment area but I have zero understanding of this and frankly am quite confused by it. I'm a drummer by trade, and would like to cover some string parts on a few no-drum ballads and earn my keep;) Anyone willing to help me out with this?

Thanks

Darren