To set the font and colour for any chart notes:

chSet 'Nfont' 'ari,8,green' © Small italic helvetica

The short code for the font is a two-letter mnemonic followed by either or both of the letters ‘b’ and ‘i’ for the bold and italic variants. The font size is in points, and colours follow the normal internet conventions.

See also ...
Colour Cycle
Fonts – defining and using short codes