Updated my Apple ID but phone is still recognizing old ID

I had recently updated my email and password for my apple ID since my old one was from middle school and now I have graduated college. Since updating though it isn't recognizing the change and when it asks to put in my password for security purposes it shows my old apple ID but accepts my new password. I am not sure what needs to happen, I even have had to restore my phone from its last backup because when I sign out and use my new ID it takes away all my photos on the new ID and don't understand why it is changing that since it is the same account?

any suggestions