"New Form" layout question

OK, I learned something, so thank you for the question. 

On Legacy forms the default behaviour is to show the built-in fields. But on new style forms it's the opposite. But to enable the display of the built-in fields you go to the settings for the form which looks like a little abacus to me at the top right and then while you're in form edit mode look for that same icon again towards the top middle and there will be a checkbox to "Show built-in fields"