Write an article based on this "Open your iPhone's Settings . Scroll down and tap Wallet & Apple Pay . Tap Default Card. Select a card."

Article:
This app is on one of your home screens. It's a few screens down. It's the first option under "TRANSACTION DETAILS." Choose the card you want your Wallet purchases to use by default. Once you select a card, you'll return to the menu. You can also change other details about your card here, including your billing address.