I am trying to allow the donor to edit amount (set a minimum) but donate more if they like. in the "donate for luncheon" box.

https://form.jotform.com/60529171575964

You can establish a minimum amount for donation, simply select the check box (while on the wizard)

Here is a demo form, the minimum amount is $10

https://form.jotform.co/21446376976870