The error “Another account from your organization is already signed in” in Microsoft Office 365 typically occurs for two reasons. One is a conflict between accounts. The other is due to cached credentials. This often happens if multiple accounts are being used on the same device. Here’s how to fix this issue:

Step 1: Sign Out of All Accounts in Office Applications

1. Open any Office application (e.g., Word, Excel, or Outlook).
2. Go to File > Account.
3. Under Connected Services, sign out of all accounts.
4. Close all Office applications.

Step 2: Clear Cached Credentials

1. Windows:
   • Press Windows + R to open the Run dialog box.
   • Type control keymgr.dll and press Enter. This opens the Credential Manager.
   • Under Windows Credentials, find any credentials related to Office 365 or Microsoft accounts (e.g., entries starting with MicrosoftOffice, MicrosoftAccount, or your organization’s domain).
   • Remove these entries by clicking Remove.
2. Mac:
   • Open Keychain Access (search for it using Spotlight).
   • Search for any credentials related to Office 365 or your organization.
   • Right-click and delete them.

Step 3: Clear Office Cache

1. Close all Office applications.
2. Navigate to the Office cache folder:
   • Windows: C:\Users\<YourUsername>\AppData\Local\Microsoft\Office\16.0\
   • Mac: ~/Library/Group Containers/UBF8T346G9.Office/
3. Delete all files and folders in this directory.
4. Restart your computer.

Step 4: Sign In Again

1. Open any Office application.
2. Go to File > Account > Sign In.
3. Use the correct account for your organization. Ensure you’re signing in with the email provided by your IT department.

Step 5: Check Work or School Account Settings

1. Go to Settings > Accounts > Access work or school on your computer.
2. Remove any unnecessary or duplicate accounts linked to your organization.
3. Add back the correct account if needed.

Step 6: Update Office

1. Open any Office application.
2. Go to File > Account > Update Options > Update Now.
3. Install any available updates.

Step 7: Use an InPrivate or Incognito Browser Session

If you’re signing into Office 365 through a web browser:

1. Open an Incognito or InPrivate browser window.
2. Go to https://office.com and sign in with the correct account.
3. If this works, the issue may be related to cached cookies. Clear your browser’s cache and cookies.

Step 8: Verify Azure AD Settings (if you’re an admin)

If this issue persists and you’re an admin for your organization:

1. Check the Azure AD settings to ensure there are no conflicting accounts.
2. Remove any stale or duplicate accounts for the user.

If none of the above works, your organization’s IT department may need to troubleshoot further or reset account permissions. Let me know if you need additional help! (Contact US)

Detailed video below: