After a Facebook password change, especially if it forces logout from other devices, you may find that Facebook.app on iOS no longer reads authentication information gfrom the iOS Settings:Facebook configuration.
You can always enter your username and password in Facebook.app, but that’s not very elegant.
Here’s how to get Facebook.app to use the account you defined in Settings:Facebook.
- Ensure Facebook.app is installed but not running.
- In Settings:Facebook completely delete existing account. It doesn’t work to enter the new password there, Facebook still won’t “see” the authentication information.
- Recreate accounts in Settings:Facebook.
- Launch Facebook.app. it should show the name of the account in Settings:Facebook and you can use that.