Ok I understand. Actually this can be applied to anything, ain't it? An admin updated the price for the product - and the customer has already paid for it. But the old price is kept fixed in the orders table, product is not duplicated every time it is being updated! This this the sensible behaviour...
In my case - the admin entered a wrong tracking url for the carrier and just wanted to fix the mistake by fixing the url. But the change is not applied to previous orders. So I need to go to SQL console and make the change from there bypassing Prestashop back office. Luckily for my clients I am able to do it.
I hope you understand
Thanks for all your enormous support
SQLyog saves us