To add a new payment method in the app tap on your profile icon in the upper right-hand corner of the map view, then tap into the "Wallet" section.
Once you can see the settings in the "Wallet" select the plus sign in the top right-hand corner. Then select "Add Card" or "Add PayPal" (only available in selected countries) and input your payment details.
Once this is complete, then tap on "Save". After you have completed this process you will see a message indicating that the data has been saved successfully. Multiple credit cards may be saved to your account.
Please note: existing payment method details cannot be changed (i.e. card details entered incorrectly). To update a payment method you must first delete the old payment method. To delete a saved payment method, tap on the payment method to be deleted in the "Wallet" section, then tap "Remove Credit Card/PayPal Account".