Had new rotors and pads (OEM) put on about 3 weeks ago. They squeak a lot when braking. Most annoying part is they make more noise when I'm going in reverse - backing out of my garage or a parking space...

Any ideas? Very Annoying LOL

 

pull the pads out, lightly sand down the corners, & put some anti squeal paste on the back.

 

Did you put rear pads in there as well? A common problem with squealing brakes going in reverse is the person that installed the new pads bent the anti rattling clip, mine is bent and does the same damn thing. This is the rear brake pads of course, if you just did the fronts, do what 2kS4 said.