It looks like you updated this page from MySQL to MySQLi and the password update line wasn't changed properly. On line 52 you have:
$UpdateQuery->bindColumn("UserPassword", "s", "".((($_POST["User_Update_group_2_Password"] != ""))?WA_HashEncryption($_POST["User_Update_group_2_Password"]):$row_SecurityAssisttblusers["UserPassword"]) ."", "WA_BLANK");
The part that refers to the old password is still in MySQL syntax and has to be updated to MySQLi, so it would be:
$UpdateQuery->bindColumn("UserPassword", "s", "".((($_POST["User_Update_group_2_Password"] != ""))?WA_HashEncryption($_POST["User_Update_group_2_Password"]):$SecurityAssisttblusers->getColumnVal("UserPassword")) ."", "WA_BLANK");
That would fix it, but there is actually an easier way to do it with MySQLi. You could just use:
$UpdateQuery->bindColumn("UserPassword", "s", "".((($_POST["User_Update_group_2_Password"] != ""))?WA_HashEncryption($_POST["User_Update_group_2_Password"]):"") ."", "WA_IGNORE");
The WA_IGNORE argument at the end tells it to simply not update the field if it was left blank. That way you don't have to set the value to the previous entry with the recordset at all.