Iphone repeatedly asking for old Apple ID sign in
Hi
I recently got a new iPhone because my old one was damaged. I restored it from iCloud fine.
My iPhone keeps asking for me to sign into an old Apple ID account, using an email that I used over ten years ago to purchase stuff on iTunes with. I'm signed into my current Apple ID fine but this old ID sign in request repeatedly keeps popping up on my iPhone, usually when my phone connects to the internet. How do stop this and remove this old email and account from my Apple ID? I seem to remember this happening before and I spoke to someone on an apple support chat and they helped me fix it, but I can't for the life me remember how and why its happening. Help would be great?
Thanks
iPhone 8, iOS 12