disable box price in orders

hello

I need to disable the price box to display the price but can not be changed. Try changing in the function

   function sales_order_item_controls(&$order, &$rowcounter, $line_no=-1)

   this
   $str = amount_cells(null, 'price');

   by
   if ($change_price_so=='1')
    $str = amount_cells(null, 'price');
   else
  {
    amount_cell($_POST['price'], false, '','price');
    hidden('price', $_POST['price']);
  }
 
  but does not save the current price when the product is changed

  What do I need? I guess it has to do with Ajax, but I'm lost

  THANKS