if the payment term for one customer is set as Net 30, can i change the payment term to for example net 60 for one of the sales orders under the same customer? or does payment terms have to be defined at the customer level? thanks all

you can change the terms per transaction

how do you do that on the sales order level? i see you can do that on the invoice

you should have a Billing subtab with Terms field; it can be elsewhere though or hidden - click on Customize form, you should be able to find it