Registration issue


New member
Hi, I'm new, so sorry if this is in the wrong place!
I got an ipod touch for Christmas. I first connected it to my regular computer, and registered it there and then, receiving a confirmation email. The next day, I connected it to a friend's computer, just to grab a few songs; I found out later that the music copied was purchased on his grandad's itunes account. On my iPod's iTunes store my default account (displayed at the bottom of the screen) had changed to the grandad's email. When next connected to my computer, the iPod would not sync with my own purchased content, claiming I was unauthorised to use it. Upon disconnection, the default account was now my own, but on reconnection, content still wouldn't transfer. On the iPod itself, it acknowledged in the application store that I had made a purchase and allowed me to download straight to the pod, but I still cannot sync applications downloaded using my computer.
Can anyone help me fix this?
Thanks in advance!