I'm working on macOS 10.13.4. When I open the App Store and attempt to update my apps which need updating, I am prompted to sign in to my apple account. However, it's prompting me to sign into firstname.lastname@example.org without giving me the option of changing that ID.
About a year ago, I modified my account to use a different email address, email@example.com. It's the same account - just with an updated ID. How can I modify the ID within the app store?