If you purchase apps from the App Store or other kinds of content from iTunes and iBooks, you have an Apple ID. If you ever need to change your address or credit card on file, you'll need to know how to access your account details.
How to view account details for your iTunes, iBooks, and App Store account
Launch the Settings app on your iPhone or iPad.
Tap on iTunes & App Store.
Tap on your Apple ID at the top.
Tap on View Apple ID in the popup menu.
You can now make any of the outlined changes to your Apple ID.
Note that if you change the country or region associated with your Apple ID and you use iTunes in the Cloud, you won't be able to change it again for 90 days. Keep that in mind if you're switching between countries.