Using classic Outlook for Windows in business environments
Hi there Siri C,
Welcome to Microsoft Community
I'm Bobadoye and I'd be happy to help you out with your question.
What you can do is to try to secure your account by creating a stronger password and enabling two step verification. A strong password contains letters, numbers, punctuation, symbols, and numbers.
Two-step verification helps protect your account by making it more difficult for a hacker to sign in, even if they have your password. Any time you sign in from a device that isn't trusted, you'll be prompted to enter a security code.
You can sign in to your Microsoft account, go to security>Advanced security options> View activity to see unsuccessful sign in and their locations, under Advanced security options you will see two step verification, please turn it on to make your account more secured.
You can also refer to the link below as a guidance:
https://support.microsoft.com/office/a4f20fc5-4307-4ece-8231-6d4d4bd8a9ba
I hope this information helps. If you have any questions, please let me know and I'll be glad to assist you further.
Best Regards,
Bobadoye