If you are tracking inventory for a product, you might want to allow customers to purchase pre-order products even if they have an inventory amount of 0.
That’s the reason why the app automatically changes the inventory setting for the product when you enable the “pre-order” feature for this product. The “Continue selling when out of stock” option will be enabled automatically:
If you do not want to continue selling products when out of stock, you need to disable the “pre-order” feature for those products.
NOTE: In the new version, the app doesn’t enable “continue selling” automatically.
So If you faced the issue, I recommend you should update to version 2 of the app. You can update to version 2 by uninstall & reinstall the app.