Check out this sample database.Open up Customers form. Be on record #1 i.e. Company A. Then click on Orders Button. This opens up Orders form which is based on parameter Query1. Orders will be filtered based on the company selected. Now click on Customers. Orderes form will be closed (and any data changed will be saved). Customers form will be on your screen.
Now go to 3rd record for Company C. Click on Orders button. Observe that Orders form now shows records for Company C.
Hope this helps!