Step 1: To update your expired credit card's expiration date to the latest one, click the gear icon at the top right and click on "Profile and Settings"
Step 2: Click on Financial Information
Step 3: Scroll down to find Debit and Credit cards. You should see the expired card there. Click on Update
Step 4: On this page, scroll down to find the credit card and it should say Expired: update. Click on that.
Step 5: On this page, just click "Update expiration date"
Step 6: Fill up the new information on the next page and click save.
Changed your credit card?
To add a new credit card, click on Add a New Card (refer to Step 4 above)
On the next page, click Add another card
You will see a form. Simply add your new credit card details there and save.