Is it possible to make Freight 1 column on Sales Order Fixed Value?

Currently this Freight 1 column on sales order has drop down that allows us to choose from values such as Freight, Insurance etc.

We would like it to be fixed for example on Freight. Is this possible?

In our case, we have actually created a new Freight type (not really freight though) called DepositFee and we would like it to be fixed column input. As soon as an item is added whenever order attrributes are changed, the column should still show the fixed value which is "Freight".

Thank you very much.