Appearance Editor

I am trying to do compile for a competition set up. I need font Aerial, point size 12 and double lined spacing. Also as i use dark mode the font does not show or print on white so please I also need to set the default font colour to black. I have tried to alter it and the only think that works is the font change. Please can someone write the YAML code for me thank you. That way I can copy it onto the file.