Most auto parts stores carry a "squeal stop" product. Loctite is one I use. Just apply to the back of the pads. I let mine dry a little before re-installing.
If the old ones did it and the new ones are doing it,you might possibly have glazed rotors. You can try the disc brake quiet and see if that helps. But if the noise is still there you might need to deglaze the rotors.
If you want some reading on how others do it. I use a special style scotch brite pads made for a drill or air powered style drill. And theyre several different colors of pads from coarse to fine you can use.