Do you see a pink button My account in the top right corner of your screen? That means you are already signed in. Do you see the button Sign in? Then you have to log in first.
When signed in, click the pink button My account in the top right corner of your screen.
Click the black button Change/Add under the header Addresses.
Click the black button Change.
Change your address details and click the black button Confirm. You have now successfully changed your address.
Attention: Please note that orders that have been placed before you have changed your address will still be sent to the old address!