Hi there! My name is Steve. I'm an Independent Advisor and an Outlook user like you. I'm happy to help with your query.
That does sound frustrating, however account security if definitely important which is why Microsoft alert you when suspicious activity is detected. I would recommend to review the sign-in activity on your account to determine if all recent logins were by you or of someone else has tried to access your account.
In order to do this go to
https://account.microsoft.com/security/ and select 'View my sign-in activity', this will show you all recent login attempts, the approximate location of the login and whether it was successful or not. If you see any successful attempts that you don't recognise then I would recommend to change your password again and update your security settings using the other links on that page.
Please let me know if I can be of any further assistance!
