The first card added to the Wallet app becomes the default card for that device. To change a default card you must follow these steps:
iPhone
- Open the Wallet app
- Touch and hold your finger over the card you want to make the default card
- Drag the card to the front of the cards in the Apple Pay section
Apple Watch
- Open the Apple Watch app on your iPhone
- Go to the My Watch tab
- Tap Wallet & Apple Pay and then Default Card
- Choose a new card
iPad
- Go to Settings
- Tap Wallet & Apple Pay and then Default Card
- Choose a new card
Mac
- Go to System Preferences
- Select Wallet & Apple Pay
- Choose a new card from the Default Card pop-up menu
For more information on managing the cards you use on Apple Pay see Apples support page: https://support.apple.com/en-au/HT205583