To change the font. Click on a desired font name in the left window of Book Designer "Change Font.
To change the font size. Click on a desired font size in the right window of Book Designer "Change Font".
add: add new font to the "font name" list
remove: remove selected font from the "font name" list
default: restore default the "font name" list
undo: reject last changes
undo all: return to the global font settings which took place before the opening of Book Designer "Change Font" window.