Show the list of the fields in your form.
When you select a field in the field list you will see the list of validation nattached to the selected field.
Use the button Add/Edit/Remove to add or edit a validation
For each field you can setup the Feedback, use the Inherited option to setup the feedback as defined in the main panel or choose a new feedback option for each field.
You can choose the feedback success icone from the list or add your custom css class
You can choose the feedback error icone from the list or add your custom css class