Did a quick search found people that had the same problem but no real solution.

My drivers side rear head rest does not fold back but the passenger side rear one does? anyone tell me why? I like having them down so I can actually use my rear view mirror and not just stare at my spare tire :P

 

the real reason the fold back is because when you put the seats down the headrests would hit the front seats. if you didn't do this already put ur front seats pretty far back and just put ur seats down. the headrests should fold back. if that doesnt work try holding the latch to the seat while ur putting them down

 

why do you need to move the front seat anywhere? just fold down the rear seat. the headrest will flip back when you're about 1/2 way folded.

and as you've probably figured out already, unless the seat is almost completely up, the headrest won't lock back in the "up" position.

 

So I tried everything you guys said and it still did not fold down

 

Really? I have mine down for the same reason. Still can never see cars behind me tho lol

Did you try folding them by hand while the seat was down with the latch pulled too?

 

try pushing the seat all the way back then pulling the latch then pushing the seat forward