How to make the form calculation widget read only?

I can't seem to figure out how to make the form calculation widget read only.  I don't want the person submitting the form to be able to change the amount in this field.  The field I am talking about is the Amount Due - Card Information Required Later field.

I watched the screencast at this page, but I'm not seeing the same options.

https://www.jotform.com/answers/1554534-How-to-protect-the-calculation-field-from-being-edited

To make the form calculation widget as read-only, please click the 3 dots below the numbers. Please check my screencast below for clearer instruction.