Dave recently updated his Samsung Galaxy S6 and now the fingerprint sensor doesn't work right. Verizon says nobody else has complained about it. Leo says that it's probably a bad update that happened over the air. It's fairly common. The only thing he can really do is to reset his phone. That will wipe the phone and reinstall the operating system. But before he does that, he should turn on 'Backup to Google' in the settings. He should let it back up and then reset the phone completely.
Another thing he can try is clearing his cache.