How to modify authentication method priority

The method priority is the priority of the authentication based on the AUTH_METHOD. Vertica only considers METHOD_PRIORITY when deciding between multiple authentication methods of equal AUTH_PRIORITY.

You can not change the method priority as they are hard coded

dbadmin=> SELECT auth_name, is_auth_enabled, auth_host_type, auth_method, auth_priority, method_priority, address_priority FROM client_auth ORDER BY auth_host_type, auth_priority, method_priority;
    auth_name     | is_auth_enabled | auth_host_type | auth_method | auth_priority | method_priority | address_priority
------------------+-----------------+----------------+-------------+---------------+-----------------+------------------
 v_dbadmin_trust  | True            | LOCAL          | TRUST       |         10000 |               0 |                0
 v_dbadmin_hash   | True            | LOCAL          | HASH        |         10000 |               2 |                0
 v_dbadmin_gss    | True            | LOCAL          | GSS         |         10000 |               5 |                0
 v_dbadmin_ldap   | True            | LOCAL          | LDAP        |         10000 |               5 |                0
 v_dbadmin_ident  | True            | LOCAL          | IDENT       |         10000 |               5 |                0
 v_dbadmin_reject | True            | LOCAL          | REJECT      |         10000 |              10 |                0
(6 rows)

See:
https://www.vertica.com/docs/10.1.x/HTML/Content/Authoring/Security/ClientAuth/PrioritiesForClientAuthenticationMethods.htm