How to properly setup coupon codes on payment form.

I have a coupon code set up... the first who tried it, it charged them anyway.  Here is what I edited since then... pls tell me if it's going to work next time or if I am doing something wrong.

I had "apply discount to" on "product", I changed it to "total".  Can/should it be on product?

I did not have an amount entered for "minimum amount to receive discount" (or whatever that question says).  Now I put in $10.

Here is the site https://www.jotform.com/build/73625593190158

Thank you!  joe

I checked your form, and the coupons are well setup. I would just recommend you to enable the "Show total price on the form":

So the users can see when the discount is applied:

Let us know if you need more help.