How can I change the email linked to my App Store?

Hi,

I had a notification to update my WhatsApp app. When I did so it asked for the password to my partners email address. I have never used my partner’s email address and apple password to download or for any other purpose. I don’t know her password.

i went to sign in settings and the only email address there is mine. I went to download another app from the App Store, to see what happened and it asked for my password alongside my own email.

How do I get around this?

also, how can it happen?

thanks

[Re-Titled by Moderator]

Original Title: Wrong email on app update