New brake problems - help

Replaced pads and rotors on my wife's 99 SE cuz they were shot and she failed to mention it to me until I drove it. After replacing parts, car still has a squeal like pads are down to the squeal pads. I wasn't sure where the noise was coming from so I changed pads and rotors on back wheels also. Still has the squeal when braking. I've changed many brakes in the past with good results on other vehicles so I'm not sure what is going on. Any ideas from the experts out there?

Did the pads come with shims on the back? If not remove the pads again and coat the back with quiet stop. It is available at most parts stores and should eliminate the squeal you are talking about.