Why does my scale shows one weight but when I ring up certain weighted items the weight on the POS is less and it only happens on certain items, not all of them – most of my items show the proper weight.

You most likely have an auto tare weight set up for these specific menu items so if your weighing a weighted item that goes into a cup for instance depending on the state that your in you may not be allowed to charge the customer for the weight of the cup by law.

Contact Vanguard Systems for your POS Sales and Service
718-921-6159