You can’t change the order of fields when you’re viewing an interface I’m afraid.  To change the order of fields while setting up an Interface, click on the Fields input on the right and then drag and drop the fields into the order you want:

Hey ​@Judy12!

As explained by Adam above, reordering can only be done on the editor/builder mode and only as shown by Adam rather than a regular drag and drop on the actual table. This was recently raised by a different user on this community. To make sure this makes it to the Airtable team I would highly suggest you request this as a Product Idea by filling out this form!

Mike, Consultant @ Automatic Nation

OK!  I suggested it. This is crazy.

Thank you for your help.