In the form editor: Preview (top bar) opens the form on its own page at /leadforms/preview/{id} so you can see and test it. The Live Preview toggle shows the rendered form inside the editor with hover buttons to Edit Field, Move up/Down, Delete Field and add fields before/after, plus desktop/tablet/mobile view switches. A Builder toggle opens a separate drag-and-drop canvas with a Builder Enabled (use builder output for this page) checkbox and Save Builder button; leave it off unless you specifically want to lay the form out yourself with that tool.