Change Invoice Item Label

I want to Change “Item” Label to “Treatments” In creating new invoice, because i use invoiceplane for my dental clinic.

Please Help i tried to change in view.php, invoice.php but no effect.

and please tell where i change coding and in which file like invoice.php etc.

I would not recommend editing the source code.
Please use the language files (application/language/english/ip_lang.php) instead. Just replace all labels there.

Thanks A Lot…