Facebook access for apps

I have the new iPhone 5S. On the phone I can get onto Facebook just fine. However, there are apps that must be accessed through Facebook. when I try to access those apps i get a message that says "Facebook server could not fulfill this access request: invalid application ID". When I go to my FB account in settings (iphone) it shows that my password is missing. The message says "there was a problem accessing your account. Please reenter the password for (my name)". When i enter the password I get the message "error signing in could not communicate with server". What am I doing wrong?