Without affecting the use of bank cards, it will be better to clean and fill them by deleting them directly or washing them with alcohol.

The signature on the back of the bank card should be signed by the cardholder himself. The purpose is:

It can prevent others from impersonating you to withdraw money or spend money on the counter. When withdrawing money or spending money at the counter, the waiter will check whether the signature is consistent with the signature on the card.

It can prevent your card from being swallowed, in case you withdraw money from the ATM, and when you go to the bank to get your card, you can recognize it as your own card. It will be more convenient to sign your name on the back of the card.