2. Credit card merchants only need to rely on the card number and the credit card security code "CVV2" behind the credit card to authorize consumption. This number is bound to the card and cannot be changed. Once the automatic renewal is authorized to the merchant, the user must cancel it at the merchant, and there is no way to cancel it from the bank. Otherwise, the deduction can only be avoided by suspending the credit card or replacing the previously authorized security code with a replacement card. Therefore, when using a credit card, don't spend it easily on unfamiliar overseas websites, and keep it properly when using it to avoid the card number and security code being known by others.

3. The credit card security code is located in the signature column on the back of the credit card, generally in the last four digits and the last three digits of the card number. Credit card security codes are widely used in credit card activation, management, transaction and other operations.