Trying to "Update Apple ID Settings"
This notification pops up all the time. After I hit "Continue" twice, a box appears titled "Enter your Mac password." Then it shows my "User Name" in faint gray letters; this is not my Apple ID. Simultaneously, it asks for my Password. It will not take my current password, nor any iteration of old passwords. What is "user name" as opposed to "Apple ID"? Whenever I encounter this, I end up hitting "cancel" in frustration. Even though I am warned that some "amount services will not be available until you sign in again," I have not noticed any curtailed activity.
iMac Line (2012 and Later)