To set the font and colour for the main chart heading:

chSet 'Hfont' 'tii,18,blue'

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.

Colours are set by name (red,green,blue etc.) or as a hex string, for example to get a nice slate grey:

chSet('hfont' 'tii,18,#3E306A')  © Slate

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