How to change Apple ID iTunes account info

You can edit the information in you Apple ID account. Use Apple ID Account https://appleid.apple.com/#!&page=signin.

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But, if you want to change your Apple ID,

See Change your Apple ID https://support.apple.com/en-us/HT202667. 

And see What to do after you change your Apple ID or Password https://support.apple.com/en-us/HT204071 (supplementary to what the fist link says)

And FYI, see  iCloud: About your @icloud.com, @me.com, and @mac.com email addresses  https://support.apple.com/en-us/HT201771

Post back if you have questions about what you can do if your Apple ID (1) is a third-party apple ID or (2) ends in icloud.com, me.com, or mac.com.