How do I make the back rest sit all the way up?

I had the same problem and sold my stroller due to MANY things.Handlebar foam ripping, no 5 point harness on mine,heavy,awkward,wheels hit every isle shopping.It took up all my trunk space,looked old and dirty fast due to me having to put it on the ground to fold and lift it!! The car seat itself that when with it as a travel system had to have a rolled up towel behind it so babies head wouldn't flop forward. I cleaned it up at took the first 50.00 I could get for it after owning it a meer 5 months.....don't regret not having it, I'd rather carry my 22 lb baby than deal with it another day.