Form publishing

Form publishing

Hi,

I want to publish a form. I can see, that the appearance of the form can be set. That's fine. 
But I want some fields to behave differently than for application users, or just want to hide some fields in the published form, because they were created for internal use only. For example if I use lookup fields in my order form for buyers and products. It is OK, if the content of the product field can be seen, but it's not OK, if someone can see the content of the buyers lookup field in the published form.
Any tips, please?
Thanks 
George