I thought it was weird since the first day that the seat does not stop where it was after letting a passenger in to the back seat. Since I don't carry my son in my car that often I have been ignoring that problem. Today I re-read the owner's manual and it states that as long as I don't fold up the backrest the seat should stop where it was before. So I tested and retested my seats and neither of them were functioning properly.
Then I raised the passenger seat all the way up and tried it and it worked! I gradually lowered it by pumping the handle bar two pumps at a time and it worked all the way down. I tried it to the driver side but it would not work. I looked at the seat rail thinking ' there must be something on the rail to stop the damn seat!'... and there it was... something that looked shiny and something that I have never seen before in my life. I pushed it up under the seat with my finger. It moved but it didn't feel loose. It felt as if it was greased up or needed more grease if you know what I mean. It didn't make metal to metal scraping sound but it was somewhat tightly held. After I did that the seat started stopping at the same position instead of sliding all the way back to hit the rear seat. I am happier now.

the way i solved the problem in all the cars i have ever owned is all back seat riders enter and exit on the passenger side.