How to change the default pdf generator font

I have simple ascii text files, can be opened in any editor; like MS Word. When I run them thru the PDF generator; either thru the adminui or the watchfolder, it creates the PDFs using the standard MS Word Font and pitch (Courier New 10.5).  I need these to be changed during PDF generation to a different font and pitch, say Ariel, 9 pitch.  Is there a setting within the PDF generator to set and/or override these defaults?  If so, where would I find it?

Thanks!