Actually i agree with the OP, I know exactly what you mean. If i do one listing with a best offer, suddenly it's the default for every new listing. And it's not just simply a matter of unchecking the box; I get the swirly waiting symbol when I do this for as long as I let run. The only way to get around it is to press Continue to go to the next page, then Edit listing to go back. Then i can uncheck the box. It takes ages and is totally infuriating.