How to change the background color?

I go in to form designer, seem to change the background but whatever i do, the form remains bright orange.

How do i change this?

I presumed you are working on this form https://www.jotform.com/210744159577362. It's a card form and is currently set to use the default theme colors. If you wish to customize it, you have to click the Custom tab in the Form Designer. Changes are automatically saved for you, but we don't recommend quitting the form builder until verified that the changes are visible when you preview the form.

Custom Tab:

At the top, below the form title/name, is the indicator telling you that the form is saving and changes saved after.

Thanks