OBIEE CSV Output format not displaying with right headers

Dear Experts

I used OBIEE To get a CSV Output format report. I used RTF template for the layout. But the the headers in the CSV format are matching the Headers used in the RTF Template. For example if the header in RTF template in PO Number in the CSV Output it is displaying as PO_Number. The spaces are filled with Underscores. How to default to actual header names in the RTF template.

Actual Output

Expected Output :

Thank you,

Anooksha