A. 1. Ensure that the coupons are still valid and have not expired. 2. Check if the items in your cart qualify for the coupon; some coupons have specific restrictions. 3. Try removing the coupon and reapplying it at checkout.

B. 1. Restart the app and try the checkout process again. 2. If the issue persists, consider using the coupons manually at the store if applicable.