Configuring preferences and options in Outlook.com
I fixed mine and I had the same issue.
When clicking on settings it will ask you to authenticate.
If I used my secondary email as my auth method using a code it would not show me the save button. However if I used authenticator app, it then showed me the save button.
I also had a secondary email address which I was part of my 365 Family package. I removed the alias on my account as being primary for my secondary email account.
Hope this helps!
Hey man. That does not really work on my side.