Oracle User Locked(Timed)

Why Oracle user get locked(timed) ? I had change profile : PASSWORD_LIFE_TIME, PASSWORD_LOCK_TIME, PASSWORD_GRACE_TIME to UNLIMITED, but it doesn’t work.

Then I run audit trail :

1. alter system set audit_trail=db scope=spfile; (then restart db)
   
2. audit connect whenever not successful;
3. monitoring via this query : 

   SELECT *
   FROM dba_audit_session
   WHERE action_name = ‘LOGON’ AND returncode > 0
   ORDER BY timestamp DESC;

4. then login fail and then locked because the user password case-sensitive, so I run : alter system set sec_case_sensitive_logon=false;
5. done ^_^