How do I change my address ?

Do you mean your Billing address?

If so, see -> check / update your billing address:

(macOS) Set up your Apple ID payment method and shipping address on Mac

Set up your Apple ID payment method and shipping address on Mac – Apple Support (UK)

or 

Sign in to your Apple ID account page and edit / update your Apple ID details -> https://appleid.apple.com

• edit your billing addres.

or 

To change the billing address you can do (macOS & Windows OS) via iTunes

Start Music (-> Click on iTunes) -> side bar click iTunes Store -> go to Account (top bar) -> View Account -> Sign in -> Apple ID Summary -> Billing Address -> Edit.

or 

(iPhone & iPad) Go to -> Settings -> tap your Profile -> Payment and shipping -> Change Address.

Edit the Address -> tap Done.

Follow the steps in the support document linked below.

click here ➜ If you need to change or update your Apple ID payment method - Apple Support

If you change your address, the credit or debit card information that you use with your Apple ID might be automatically updated by your financial institution, and you don't need to take action. But if there's an issue, add a new card first, then remove the old card.