
Hello Jess,
If someone is trying to access your account, the most important thing is to secure it as much as possible. Since you’re aware that the person attempting access is located in the United States, I’m assuming you still have access to your account and can monitor login activity.
Try resetting your Microsoft account password at:
https://account.live.com/ResetPassword.aspx
I recommend doing this in a private/incognito browser window to avoid any issues related to cached data.
Once you've changed your password, enable Two-Step Verification (2FA) in your Microsoft account's security settings. This will prompt you for an additional verification code (via text, call, or an authenticator app) whenever you sign in from a new device, helping prevent unauthorized access. It’s definitely worth enabling, at least temporarily. That way, the account will be protected against any threat.
After securing your account, sign out of all other active sessions. Also, make sure your recovery email address and phone number linked to your Microsoft account are both secure and up to date.
Best regards.