This took me DAYS to find. When I was trying to find the Kiosk Mode for my iPad, there was no obvious way to get into the edit screen. I have been unable to find any information on getting into the builder section or into the editing section of an individual form. I only found it by testing various arrow (no luck), looking around each form and finally, swiping the one of the form titles, revealing the Builder module and 3 dots beside it. 

Swiping the "Test" form line to the left revealed the Builder link and 3 dots beside it. 

I've been looking to Kiosk Mode ever since I loaded the app on my iPad. Click the 3 dots to reveal all the general form editing, including Kiosk Mode. Finally!

Clicking on the Builder Link  reveals the ability to edit the fields on individual forms. 

I hope this helps anyone who has been trying to find this important aspect of Forms