Thanks for reaching out to the Apple Support Communities! It sounds like you are still seeing your old Apple ID and need to change to the new one in the iTunes Store. Check out this article with steps to follow to Sign in with a different Apple ID on your iPhone, iPad, or iPod touch . Specifically:
iTunes, iBooks, and App Store
- Tap Settings > iTunes & App Store.
- Tap your Apple ID. If you see the option to Sign In, you can change your Apple ID now.
- Tap Sign Out.
- Go to Settings > iTunes & App Store.
- Tap Sign In, then enter your Apple ID and password.
If you changed your Apple ID to share content with a family member or because you have multiple Apple IDs, try Family Sharing instead. With Family Sharing, you can link your family's Apple IDs into a group that can share purchases, photos, and more.
Keep in mind that any purchases made with the original Apple ID will need to be made again with the new Apple ID.
Have a great day!