Wher possible, forms use HTTPS. However, depending on how the form has been shared, this may not be possible.
Situations where forms won't run over HTTPS:
- If the page or form is embedded in a site that isn't running over HTTPS
- If the page or form is running as a pop-over on a site that's not running over HTTPS
You don't need to do anything to a form to make it run in the right mode - it's automatic.