1. Go to your Subscription & Billing section.
Note: The Subscription & Billing section is only available for accounts with existing paid subscriptions. If the account is on the Free Plan or still under the free trial period, kindly refer to this link on how to upgrade your account
2. Under the Payment Method, just click the +Add payment method link and enter your credit card information.
3. Make sure to tick the "Use as default payment method" option then click the Add button.
4. Once added, you will see that you already have 2 payment methods on the record. You may delete the old credit/debit card by clicking the 3 horizontal dots beside the old card's expiration date and select the Delete option.