When buying Bitcoins with a credit card from either the Coinify platform or your Blockchain wallet, you will get to a screen which asks you to enter your card details to complete the transaction. On that screen, you are presented with the following options.
If this is your first card order, you can click on 'Save card' for later use.
If you have completed a card order before and have saved your card details, you can choose a saved card to make the payment or click 'Add new card' at the top right.
You also have the option 'Delete card' on the bottom left.