How do you change your iTunes username and password on your iPod?

My friend gave me her iPod because she got a new one. I just made a new iTunes account with a new username and password. How do I change her username with my new username? Please help! Thanks :)

theres no way ive tried that

yes there is you go to app store click on the first tab to the left the feature one and scroll all the way to the bottom and sign out.
your welcome

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