changing feta23 fonts

[darkijah]

""The Feta font provides musical symbols at eight different sizes. Each 
font is tuned for a different staff size: at a smaller size the font 
becomes heavier, to match the relatively heavier staff lines. The 
recommended font sizes are listed in the following table:""

Where do I find the option for these fonts to change them - I don't seem 
to see anything on the page: 
https://lilypond.org/doc/v2.18/Documentation/notation/setting-the-staff-size

Dearly regards
tired Darkijah that should go to sleep and stop playing with Lilypond :P

*Morning with kick start coffee*
Can see it did not show up, had send it to the wrong email - still 
clumsy about these things.