Default condition when saving PO

Hello everyone.

in our company when someone saves a PO with a condition like vendor discount, system automatically remembers this condition and its price. then for the next PO from that vendor, it automatically puts that condition in it. while these 2 POs are not related. Just the vendor is the same.

I have checked parameter EVO in users and they all have it as EVO = 01.

what can I do?

Many thanks in advance.