Managing personal Outlook.com account settings, security, and privacy
Hello Scarlett, i'm Timon and i'm glad to help you.
Your account might be compromised.
You can check your Microsoft's account activity here: https://account.microsoft.com/security/
You will find some useful information, such as the date your account was accessed, by which device, with which IP address.
If you find something wrong, i strongly advise you to change your password and recommend to use the two-step verification.