As above, the first option in the CIFS settings dialog is NetBIOS Name. There isn't any option in the CIFS Settings to set the Authentication Model.
See the attached screenshot.
This is causing a problem for me as I appear to be running into the same issue as bug #3396: https://bugs.freenas.org/issues/3396 Oddly, smb4.conf shows the authentication mode set to use as I would expect.
Prior to upgrading to 9.2.1 (and, subsequently, 9.2.1.1), my shares worked fine. Now I can create and delete files in shares, but I can't write any data to them.
It is now like this: The "Authentication Model" field has been removed from CIFS as Anonymous is not a valid setting for Samba4. Instead Local User is used unless the system is joined to an Active Directory domain.