No matter how I configure the font settings in Easyworship 6, it dosen't applies to any songs in my list. Is there is any ways to make this happen?
Each songs seems to have different fonts and size....help.

If songs have different fonts they are not using the system default font. You should create a Theme that uses default font and apply it to songs. Once song is using default font you can "change" it using Edit -> Options -> Live -> Song Font.