Discount Ninja supports two checkout modes:

To change the checkout mode to discount code mode:

In "Draft order mode" Discount Ninja uses the standard APIs provided by Shopify to prepare a discounted checkout. This checkout mode uses draft orders to provide the most flexible checkout experience. The checkout screen provides the clearest overview possible so that customers can easily understand how discounts are applied to the checkout.

Note that this mode has a number of limitations:

In "Discount code mode" the app creates unique discount codes that are applied automatically at checkout. The discount code combines the benefits of all promotions applied to the cart. This can be useful for customers whose backend systems cannot handle complex orders with custom discounts and instead require orders to use a single standard discount code. The visitor is sent to the standard Shopify checkout, which features a 'Return to cart' button. This mode does not support combining free shipping promotions with other (percentage or fixed amount) promotions. To avoid bypassing the rules of your promotions the app detects situations where the visitor returns to the cart after visiting checkout. When the visitor is no longer eligible for a discount after changing the content of the cart the app will void the discount.