Any object created by DropSpot is associated to a metadata form. If there is no specific form, it uses the default one (with free text)
At the moment, you can edit the info in that form at any time on an existing file but you cannot associate an object with a form that was created afterwards. The link between an object and a form is permanent although you can change the values in the form at any time.
Support Admin
About metadata in Dropspot