The product at the top of the page is the current product set for merchandising. When the sales event is over, the product at the top will automatically be shuffled back to the bottom of the list.
When the product is shuffled to the bottom of the list, the default sales quantity will be based on the previously set quantity, unless you manually update the value. This will prevent you from overselling an item at a discount.
If you wish to force a product into the live sales event, simply click the reorder icons and drag the product to the top of the list and click save. This will immediately push the product at the top of the list out to the Deals page.
Droparoo tracks whether a product has been merchandised for the given sale. Changing the timezone within 24 hours of the sale time may cause some confusion.