This is the one seat I never have trouble with. I bought it for my Mom in her car because it's so easy. Anyway, that's an obnoxious and unhelpful reply, lol! What I do is loosen the latch straps completely, latch both sides, and put the seat where I want it. Then I push into the corner of seat near the strap that says "pull first" and I pull it up and towards the seat. The second latch strap, I pull down towards the vehicle seat while pushing on the car seat near that corner.
Hope that made sense. Works for me!
DD1 9 yrs old 12/2011
DD2 7 yrs old 01/2014