Cash app has its self locked pin to keep your account safe and secure. Even, you are also eligible to create a locked pin here. You can use anyone from Touch ID, Face ID, PIN, SSN, etc. It is basically work as peer to peer payment. So, you can trust, because the transaction is only visible to sender and receiver. Go ahead to use Cash app number. https://www.yahoocustomer-service.com/cash-app-customer-service.html