the forum can only set
User area(Is the user area (user list, profiles) accessible public?)
by two options, that's,
1.public accessible
2.accessible by registered users only

I think it is not good for user to visit Admin or Moderator's profile
For Admin, he can visit anything but for the user whose user_type <2,
I think they can only see those whose user_type <2.
so I made a change in the file includes/user.inc.php

just after

<?php
if(!defined('IN_INDEX'))
{
header('Location: ../index.php');
exit;
}

I add in:
------------------------------------------------------------
//add by chengtr for user area's visit attribution

if(isset($_SESSION[$settings['session_prefix'].'user_type'])
&&($_SESSION[$settings['session_prefix'].'user_type']==2))

$level_above=3;

else $level_above=2;

------------------------------------------------------------
and then in this file, in every sql sentences which inlude ".$db_settings['userdata_table']."

I add in:
------------------------------
user_type < ".$level_above."
------------------------------
in the 'where' conditions of the query sentences.
(remember AND before or behind this)

after these 2 changes, any user can not see the Admin's information.