You can use the following to check if you have logged into Office 365 on your desktop.
From Office for Desktop
If do not already have an Office file open (such as a Word document, an Excel spreadsheet or an Outlook email), open Word, Excel or Outlook on your desktop. Open an existing file/email, or create a new one.
For Word or Excel, select File > Account.
for Outlook, select File > Office Account.
Check what is displayed under your User Information
- If you are already signed in, you will see the Sign Out link.
- If you are not already signed in you will see the Sign In link.
To Sign in
Click the Sign In link.
In the Sign in pop-up, type the email address and password you use with Office. This would be your FYI account associated with Office.