How to change my credit card on my account?

I was trying to upgrade and add a new credit card and it wouldn't allow me to make changes to my account. 

And I do not want to over charged for payment to my old account for INF. 

Kindly go to your billing page https://www.jotform.com/myaccount/billing and click on "Change Credit Card" button and input your new card number.

Once done, try to upgrade again and see if that works. Let us know how it goes.