Enable Backorders

    Allow users to charge customers for items that are not currently in stock. This is useful for businesses that order products for customers after they make a purchase or businesses that take a bit longer to update their stock quantities.

    1. Go to Settings.
    2. Press General Settings.
    3. Scroll down to the Stock Management section.
    4. Select Enabled under ALLOW BACKORDERS. 
    5. Scroll down and press Save.