[Admin]

In functions.php replace:

  global $allowhtml,$allowbbcode,$allowbbimagecode,$allowsmilies;

  if ($forumid == 0)
  {
    $dohtml=$allowhtml;
    $dobbcode=$allowbbcode;
    $dobbimagecode=$allowbbimagecode;

with:

  global $allowhtml,$allowbbcode,$allowbbimagecode,$allowsmilies,$post;

  if ($forumid == 0)
  {
    $dohtml=$allowhtml;
    $dobbcode=$allowbbcode;
    $dobbimagecode=iif($post['usergroupid']!=6, $allowbbimagecode, 1);

That should work.