Page back question

[lemmerdeur]

Untill 2 days ago, when I was on the Internet and using the page back arrow of Mozarilla fox, it woulg go to the previous page wher I left it. Now, it goes to the previous page but to the top of the page. I am sure that there is a setting but I didn't change anything and I would like to reset it where it goes back to where you were.