Changing headnote design

I use the headnote designer (in the Edit menu) but I cannot find the drawing I want, that is to say an empty square with a cross inside, that could be put on black notes (i.e. quavers, semi-quavers and so on) or even ops white notes as well.
More, how can I draw my own headnote design?

The notehead sets editor can be found on the Engrave menu and is documented here.

Thank you very much Pianoleo. I’ll work on it.