S.C.
We have two Evenflo Titan carseats and I struggled with the straps initially as well. However, I forced myself to sit down and read the pamphlet and toyed with the straps (without my child in the seat) and have now mastered them.
The fact that you have to adjust the straps from both the bottom and the top is a bit cumbersom. And if you adjust the top then you have to readjust the chest buckle. I think I must pull the straps out from the bottom at least once a week and then have to adjust the top and chest buckle all over again. However, it was well rated by Consumer Reports (2006) and, overall, we're pretty happy with them. Now if only I could afford a mini van!!
Best wishes.