I have a HP Deskjet 6940 printer. It works very well but how do I get it to print in black and white? Both are

in the printer (color and black and white cartridges) but when I print coupons and such I don't need them in color. Is there a button you push or an option after you press print?I have a HP Deskjet 6940 printer. It works very well but how do I get it to print in black and white? Both are
the two buttons,black and color are located on top of the machine near the lcd display....just press the black button and you are set.I have a HP Deskjet 6940 printer. It works very well but how do I get it to print in black and white? Both are
you hit the black button instead of the color one