but the use case is not the correct procedure.
form builder is not intended for editing existing forms
it is a form builder
not a form editor.
it is intended to be used to create a form.
you are using it to edit a form that is already created. that is not the intended use case for form builder.
if you have a form that is already created, you need to add the functionality to it manually rather than try to use form builder to add the functionality.