[Scott MacVicar]

change
array_splice($oldnames,4,4, addslashes($username));
to
array_splice($oldnames,4,4, addslashes($bbuserinfo[username]));

AND

array_push($oldnames,addslashes($username));
to
array_push($oldnames,addslashes($bbuserinfo[username]));

AND

$DB_site->query("INSERT INTO namelogs (userid, usernames,lastchange) VALUES ('$bbuserinfo[userid]','".addslashes(htmlspecialchars($username))."', '".time()."')");
to
$DB_site->query("INSERT INTO namelogs (userid, usernames,lastchange) VALUES ('$bbuserinfo[userid]','".addslashes(htmlspecialchars($bbuserinfo[username]))."', '".time()."')");
will modify original now.