Yamaha DTXpress/DTXplorer/DTXtreme

Hey people, hope you had a safe new year!  OK I've got a question 
about rim switches.  In the instruction book for the DTXII it has a 
section where it lists all the pre-set drum kits and there sounds.  
I think in all of the kits it claims the kick pad or bass drum to 
have one sound and then a rim switch sound.  For example I remember 
one kit had a normal bass drum sound and for a kickpad rim switch it 
had a cowbell sound.  So how do you get the cowbell sound off of the 
kickpad?  How can the kickpad have two sounds in the first place?  
I'm confused!  Thanks a bunch!