At present it is not possible to disable the 'Select All' function for checkbox fields. It would be very useful to be able to deselect/disable this functionality for each checkbox field in the Admin layer of the form builder.
Yes! This should absolutely be a setting we can turn off -- preferably on a case-by-case basis for each checkbox field, and it is extremely frustrating that the preview feature in the custom form builder doesn't accurately reflect how a form will appear once it goes live.
