Matt Feeney posted an idea to the support portal that I need help promoting.
Ability to order custom fields in Campaign Settings
Currently there is no way to reorder custom fields in the settings. For a user the logical order of fields on a form is very important. The only way to do this currently is by deleting all your fields and recreating them in the order you prefer. This will also require you to re-configure your external calls and possibly loosing data.