You sure your dad isn't monitoring your internet surfing too? I bet he's countering every move people are posting here.

He knows nothing about computers, proof? He actually has a PPC iBook

I'm much better with computers, I'm just worse at explaining why I use 100 GB of bandwidth (20 or 30 GB of upload :O) every month.

Quote from dawesdust_12 :

70 GB of experience.

Hahaha

I've been watching this thread for a few days, unable to make up my mind. How to perform such tasks is common knowledge and I would help you if you had legitimate reasons, but I can't see anyone really good at the moment. The fact that it would be you (and not me) to have complete responsibility for an action that you may do doesn't help.

I'd leave the computer as is, in this case. You may not like the idea but I don't have any good reason to question your father's authority or to suggest a complete solution to your "problem".

Anyway suggesting to change passwords is a bad idea. There are methods that don't involve password changing and that leave no obvious traces because you can undo them all. How to perform such an easy task is a complete different matter that won't be discussed in this thread, at least by me.