How to automatically login to Facebook on my iPhone 4S?

I had to replace my iPhone 4S today and when I synced the new phone some of my settings weren't transferred even though I backed the old one up. I had my Facebook app set so that I could login just by pressing "login" when I opened the app. No need to enter my password every time. Now that I have the new phone it's set so that I have to enter my password every time. Does anyone know how to change the login settings so that it remembers your password and all you do is press the button? I can't remember how I changed that setting the first time and I don't want to enter my password every time. Very annoying.

I'm sorry I don't know about that but why do you even log out. Just stay logged in. Since you want your password to be already there I'm pretty sure that your phone is private and no one can go through your phone cause you have a lock on it so why bother logging off

This is a worthless answer.