Hello,
sorry this is not natively possible, however we can send you a way to do it with a simple code change. let me know if you are interested.

Hi

Thank you for helping.
Yes, i'm interessted.

Best regards
Christoph

Hi and sorry for late response.

Please follow these steps:
- Copy file from /administrator/components/com_jsn/views/users/tmpl/default_export.php in folder /administrator/templates/isis/html/com_jsn/users/ (create if not exists), this will create an override for the export file
- open new file and add at line 47 following code

$export_fields = array(

	'id',

	'name',

	'firstname',

	'email',

	.....

);

You need to customize the array to insert manually the field to export with the order that you prefer