Updating my credit card does not save my changes for security code and expiration date.

Security codes are never saved; it’s a security feature of credit card validation; merchants are not permitted to save the security code. In fact, a new optional security feature of the Apple Card is the security code changes every few days, so if anyone DOES save it and reuse it the card validation will fail. The first time you use a new card the CVV is validated; after the card has been validated for a specific merchant or device it doesn’t need to be validated again. The expiration date should be saved when you update it, unless the card validation fails.