Select "Pay using a different credit card" when submitting your next project.
If you want to update the credit card details without opening a new project, you can simply purchase account credit (any amount) using the following link: https://www.onehourtranslation.com/payment/quote/?amount=10000
The credits will be saved in your account and can be used to open new projects at your discretion.
Only the latest card details will be shown to you on the payment page. You will not be able to choose between different saved cards.