Unable to type anything into Simplified field notation

When I used an older version of Adobe Acrobat (I do not know which one, my office updated to Adobe Acrobat Pro DC without notifying us first so I no longer have the old version or anything that tells me what it was) I was able to input simple equations into 'Simplified filed notations' under 'Text Field Properties' such as (Name_of_Text_Field*2) or (Wallet*2) with the Text Field being unlocked so that the client I am sharing the file with will be able to input the amount of Name_of_Text_Field and it will then calculate the cost (e.g. count X $2) and they will get a total. Now while I get a courser in the 'Simplified filed notations' box nothing I type appears; I can click the edit button and the 'Create and Edit JavaScripts' appears, however, I do not know JavaScripts so nothing I type in there creates the simple calculation I need.

In another form I saw the suggestion of going to Edit -->Preferences-->JavaScript-->select Enable Acrobat JavaScript when someone else wrote they were unable to type anything into 'Simplified filed notations' , however, I did that and found that there was a check mark next to Enable Acrobat JavaScript

Sorry I cannot be more clear. I am self-taught on a number of products we use and not a computer programmer or anything similar to that.