If you want to edit the Multi Select option in the TYPE part of your custom form, you can bind the multi select field to the selection fields by marking the Bound to another field box. And, you can edit the Bound Field Value part based on the options you created in the Selection Field, you can set the details appropriate to the value part from the Options section.
If you want to edit the Selection option in the TYPE part of your custom form, you can bind the selection field to another selection field by marking the Bound to another field box. And, you can edit the Bound Field Value part based on the options you created in the Selection Field, you can set the details appropriate to the value part from the Options section.