Ok, my Apple ID for iTunes is XXXX@yahoo.com and it has been for at least the last 5 years. My iTunes account works fine from a laptop, but all three of our iPhones are showing an Apple ID of XXX@XXcsh.com which is an email address that I haven't used in 10 years. If I go under iCloud settings with the phone the information is correct and the cloud works. When I try to update an app, the phone indicates I am using the XXcsh.com account and wont accept a password. All of the phones are 4g or better and the software is up to date. I have tried to re-sync the phones and that does not work. I have looked in settings and can't find a place to change it. Apple says the phone will pick up the last used account when you sync it, but that is not working.
How do I get my iPhone to go to the correct account?