Order the list of the attached files at the issue to prepare the export
As a Jira user, In the display screen of an issue, at the middle right, click on the icons
to order files from top to down or positioning between the files
When you click on the icon 
: the file will be positioned at the top of the list
When you click on the icon 
: the file will be positioned at the bottom of the list
When you click on the icon 
: the file will go up from a place
When you click on the icon 
: the file will go down from a place
Changing the order of files has no impact on the order of attached files to the Jira issue, it's just a way to define the processing order of the export of files by our plugin