Facebook notification problems on iPhone?

[anonymous]

I recently got a new iPhone 4S. I downloaded Facebook and I can use that app fine. However when I open the app it says I need to update my password for my account in the settings. When I go to do this, it says that it does not recognize my password. When it asks for my account name it automatically says my old one. (I changed my "facebook username" a few months ago.) I have not found a way to make my phone recognize it yet. I've entered the correct password numerous times. I have tried changing my password, using my old passwords, restarting my phone, deleting and redownloaded the facebook app, logging off and back on, waiting a few days, and checking for the latest version. I have no clue why it's not working. Any suggestions?!