You cannot directly edit variables there are only two ways to modify the value of a variable:
The Set Variable script step and the Let function.
If you want to directly edit a value on a layout, you have to use a field. To use that method to modify the value of a variable, you'd have to put a field on the layout, copy the value of the variable to it, edit it and use a script to copy the value back to it.
And to review the value of variables without using FileMaker Advanced's data viewer, you'd have to put merge variables on a layout. If you have a global variable named $$GlobaVariable, you can put this layout text on your layout:
Note that this is the same format that you would use for a merge field, but with the name of a variable in place of a reference to a field.
Okay, I misstated my question. I've gotten sloppy in my design and short of going through all of my scripts (guessing now that the pros have a notebook of their scripts...) I just wanted to find out what $$variable names I've used. Is there a place that has that list? I DO understand that I won't be able to make modifications to those variable within the list (if one exists).
Thank you all for your patience.
That's not something you can do. We "Pros" should be using FileMaker Advanced where we can use both a Database Design report and third part produced tools such as Base Elements to track this and many other design elements.
Note: even a database design report does not just provide a place where all such variables are listed in a table--though that would be a nice new feature, the the data is there to be searched out in more cumbersome fashion if the need arises.