Using our new UI? You might want to check this help article instead.
In case you are on a recurring subscription, the card that will be used for renewing your plan automatically is the card you added as your default payment method.
If you want to use a different card for your recurring subscription you will need to set a different payment method as the default.
Keep in mind that it is best for this change to take place a few days before your billing plan is to be automatically paid, so that you don't run into any issues that impede your plan renewal and prevent you from being able to send your campaigns on time.