IPod can see messages sent on iPhone?

My sister just got the iPod touch and she synced it on the family computer that all our other apple gadgets are on. She can now see all my iMessages I send and receive. How do I stop this? I don't want her reading my messages.

You have to get her an account for her. You're on the same account.xx

Don't let her sync it on the computer or you get your own computer and sync it there. If you choose the latter, deauthorize your information on the family computer.