If you doing your study with a UK CAA controlled FTO, then you need to do your exams in a UK CAA controlled exam centre. This includes the one in Florida.
The application forms are slightly different and the fee is £84 per exam. You must apply through your CGI in the normal way.
Do a google search for CAA International. Then download the application form.
The deadline for this centre is one full month before the exams so you must plan ahead.