I had this problem as well noticed last year. Apparently it’s a manufacturer defect. I replaced both front windshield and rear windshield and haven’t had any problems yet. This is commonly caused by the sealant becoming weak, which in my case was this.
If you're talking about folding the backrest part of the seat down/forward you have to slide your hand in behind the back seat up near the headrest and feel around for a teather string, pull it up and pull the seat back towards you. Same thing for both sides. As for your leak if its the 3rd brake light your headliner will be wet too. If not then its probably the notorious leaking back window.
Thanks for sharing that. I didn't know they folded forward like that, and not sure what the purpose would be. I only knew about the reclining feature, and being able to lift the bottom seat portion up.
There's also a vent in the back wall of the cab (between the cab and the bed) - maybe check to make sure it didn't get something stuck in the flap and wedged open.
