Login from location I am not aware of.

[Kaushik Dash]

So basically I have noticed this happening since a few weeks.

In recent activity of my outlook.com account (also linked to my windows phone and previously this wpcentral account), it shows that somebody from the USA didthe security challenge. I have changed my password several times but it still shows that some body from the US did the security challenge. Note that just about the same minute before the security challenge by the US ip, there's successful log in from my ip.

Is it something that I shouldn't care or something I should be worried about?

 

[Reflexx]

Have you tried changing your security challenge question along with changing your password? Also look at your trusted devices and make sure they are all yours.

 

[Kaushik Dash]

I am not sure what the Security challenge is. If its the security step to access Preferences, permissions, recent activity pages, then its set to "send code to my phone number". Now obviously they will need my phone to access that page, and my phone is with at all times.
I have changed my passowrd several times, but that IP still shows up in recent acitivty.

And how (or where) do I find out which devices or IPs are trusted in my account?

 

[jmshub]

I'd also suggest enabling two factor authentication. I use the Microsoft Authenticator app to log into all of my Microsoft accounts, my gmail account, and my LastPass.