How do you switch grip shifters from shifting as if they were on the opposite derailleur? I was replacing cables on grip shifters recently and when I put them back together they acted as if they were on the wrong side. By that I mean the front shifter (3 chain rings) were shifting 7 times and the rear shifter (7 speed) was clicking 3 times. I was baffled at this and did not know what was wrong. Is there a way to change them back?
It sounds like you have accidently mixed up the cables and routed the front dérailleur cable to the rear shifter and vice versa.

You can change them so that the front shifter goes to the front dérailleur pretty easily. Just swap them at the shifters.