How can I allow users to manually enter the amount of the donation they want to give

I am trying to add a field to my payment options for Donations.  I would prefer to have it as a “fill in the blank” amount that caluclates and is charged in the total but I would also be happy with payment increment options (ie: $0, $5, $10…).  However, I cannot figure out how to customize this field.  Please see my print screen attachment below.

Thank you,

Monica  

Unfortunately, it's not possible to set a random (manually entered) price for a product.
If you want to allow your submitters to set a value manually for the payment you would need to use the Custom Amount Payments setting in your payment tool.

On this scenario, you'll need to take your product list outside of the payment tool and then you can add a field to allow your users to manually enter a donation amount and use the Form Calculation widget to calculate the total amount that needs to be charged using the payment gateway. Please check the following guide: https://www.jotform.com/help/259-How-to-perform-calculation-in-the-form

If you have further questions, please let us know.
Best Regards.