Please tell me exactly where the shoulder straps should be

[cookiemonster80]

I have a both kids rear facing in britax marathon and blvd at the moment but am always confused about which slot the shoulder harness should be in- should it be below the shoulders? Above? Is there a place I can look to see a picture of where they are adjusted correctly? DH insists they are placed correctly but I'm just not sure- we live in a small town- no car seat techs around to take a look and when I took them by the fire stations and police stations for them to check they looked at me like I was crazy.

We are going on a long trip tomorrow and I want to be sure they are adjusted correctly before we leave.
TIA!

[edurnemk]

They need to be at the level of the shoulders or below for rear-facing.

[BDKmom]

http://treadingragingwaters.blogspot.com/2012/02/11-deadly-mistakes-you-didnt-know-you.html

Someone linked to this the other day, and they have a good illustration under #6.