I Need some help

Ok well here it goes my Mom and Dad just got a New Computer and they were trying to use there Old MacAfee Disk (the 2001 model think it was) well of course it wouldn't update, due to its age and i was hoping to us my Norton disk to give them the 15 day Trial to keep them protected till they can get there own.   It should of worked out just fine as long as they didn't hit the register CD key button right? As it was described on the back of my CD Key label BUT as soon as they logged on it Auto Registered.  And so i tried to just download the 15 day trial here.  uninstalled the one that came from the disk but the CD key just register the 15 day trial one... x_x so how do i fix this?   and to make matters worse it reset my subscription on my computer my computer had 220 days or so left and it just reset it.  so what i'm asking is how do i fix this mess on my computer and on my mom and  dads computer all i wanted to do is help my mom and dad out and keep there new computer safe.  it all i've caused was headache for me.    So what do i to fix all of this?