Thank you for your post.
When you tap export, and "Export Setup" window appears. The third item down is the Fields. Tap this to select the fields. Although the fields originally appear in alphabetical order, there is an icon to the far right of each field. Tap and hold this icon, and then drag it upwards or downwards to the position you want it to appear in the Excel file. Once you get the field order the way you want, click "Done" and continue on with the other options.
Let me know if you need additional clarification.