Is there a way to change the default font in Author View

I've just started looking at FrameMaker XML Author as an editor for DITA. The font used in Author View is very hard to read as it's very light and thin. Is there a way to change the font to Arial or another sans serif font. You can change the font of XML View, but not Author View. ! I've tried zooming in but it hasn't helped. Here is a small sample of what it looks like at 100% zoom.