Sugar,If you want to correct just one drum note and not all drum notes you are at the right place in "Edit" tab.
(lets say the rhy1 part goes "tick-tack" and you want to lower the voice only of the "tick")
But you got to do it individually for all variations if they have different drum patterns.
If you want to lower the volume for all the drum pattern of Rhy1 (both the "tick" and the "tack")
then you are at the wrong place in edit tab.
Just call up the Mixing console to lower the voice of the Rhy1 as Ed B suggested.
Sorry for the ...."tick tacks" I always forget which is which in drummers language (snares,toms etc)
I hope i didn't confuse you