How do I fold the rear seat down flat on my 2012 silverado extended cab?

SOURCE: Rear seat won't fold down (60 part of 60/40 seat)

I had the same problem on my '03. The seats would not fold down using the latch release as I had always done. So I tried a combination of pulling up on the side latch AND the top latch and the seat folded down. It really doesn't FIX the problem but circumvents offending  defective part. I will use this method until it doesn't work then I might shell out the $$$$$ to the dealer.

SOURCE: 2001 olds alero rear seats

There shouls be 2 straps inside the trunk at the top. Both on the driver side but one is for the left side and one for the right side seats. Pulling on the straps releases the 'lock' that should then allow you to pull down the seats from the back seat area.

SOURCE: rear folding seat belt locked

get your dealer to replace the seat belt, depending on age, should be under warranty. Belt is defective. I have a g 2003 vue, and my dealer replaced the belt for no charge.

SOURCE: hOW DO THE BACK SEATS FOLD DOWN

There is a latch located behind the head rest on the rear deck area of the car. Good Luck

SOURCE: Fold down rear seats

THE SEAT RELEASES ARE IN THE TRUNK IN THE AREA WHERE THE SPEAKERS ARE NEAR THE EDGE OF THE TRUNK OPENING.