The first card you add to your Wallet app is your default card. If the first card you added wasn't your Barclaycard, you'll need to follow these instructions:
- go to Settings and select Passbook & Apple Pay, or Wallet & Apple Pay
- tap Default Card and select your Barclaycard, to make it your default for payments
You can also change a default card, by choosing the card you'd like to make the default, and dragging it to the front of your Wallet app, then tap 'OK' when prompted.