Open up All Styles, and you'll see styles called "Comment Text" and
"Balloon Text." (I haven't yet seen an explanation of the difference.)
Right-click, choose Modify, and then change the font either on the
opening panel or by clicking More > Font.
To get to All Styles, go to Styles & Formatting (Ctrl-Alt-Shift-S),
Options at the lower right, and the dropdown called something like
"Show What?" (You'll probably want to set that back to what it was,
since All Styles shows you a LOT of styles you have no need for.)
