Welcome to Apple Support Community!
There are steps that Apple recommends you complete after changing your Apple ID email address.
> What to do after you change your Apple ID or password https://support.apple.com/en-us/HT204071
If you are still signed in with your old Apple ID, you can just sign out of the device and sign back in using the current Apple ID email.
Your password should not have changed.
If you are unable to remember the new Apple ID that you created, you can visit iforgot.apple.com and tap on look It up.
> If you forgot your Apple ID https://support.apple.com/en-us/HT201354
hope this helps