New form style: How to change the default style?

When I create a new form or clone my existing form, it defaults to a style inconsistent to my other forms, which were made in Default Theme. 

The left side of the screenshot is the Camper Code of Conduct (which was made in Default Theme) and on the right is a blank form showing the new default.

Even when I clone an existing form it changes it to the new default.

Apologies for the confusion. You are able to change the default theme on your account's settings. Please go to your account's settings and change the form layout option from "Single Question in One Page" to "All Questions in One Page".