If your brakes are still squeaking after you replaced the brakes it could be caused by brake dust being trapped between the brake rotors and brake pads.
Sometimes there's brake dust on those surfaces that you might not be able to see fully and it's a good idea to use some brake cleaner that sprays on the brake rotors and then it evaporates and you can use a paper towel or shop towel to wipe the rotor clean.
Another cause of the brakes still squeaking is that the brake pads are not retracting back properly due to a bad brake caliper.
Or the brake rotors could be warped that are causing the brake pads to touch the rotors as the brake rotors spin.
Sometimes it's normal for new brakes to squeak for around 1,000 to 5,000 miles as the brake pads wear down.
If the brake squeaking or squealing continues after 5,000 miles of driving on them then you might need to take them apart and check them out.
The squeaking is mostly just annoying as long as the brakes are working properly.