You can enable it after entering the password in Me - Manage Account -Fingerprint Payment (FaceID Pay) and verifying the fingerprint (face) successfully to replace the password entering when sending transactions. But you still need to enter the password to change the password, enable the blockchain feature, synchronize account and other account management operations.
If the fingerprint (face) in the mobile phone system has been changed, it may cause the fingerprint (face) payment in MYKEY to be invalid, please reset it as above.