One field columns are not displaying correctly in Preview

In the editor, there are no issues with fields in my new form. But when I select Preview Form, the Ethnicity field overlaps with the field next to it. I can't figure out why. I have not published it yet and it seems I can only attach one screenshot for you.

You seem to have changed your form theme. The Ethnicity* field is now at the bottom part. To set up a form column, you need to use the manage field feature. We have a guide for that, check that here: https://www.jotform.com/help/423-Setting-up-Form-Columns.