Make Microsoft 365 open all files

The system needs two things to open all Microsoft 365 files:

1. a correctly activated Microsoft 365 Personal subscription, and
2. the Microsoft 365 desktop apps set as the default apps for those file types.

Follow these steps in order:

1. Confirm the subscription is active and associated with the correct account
   • In a browser, go to https://www.office.com.
   • Sign in with the same Microsoft account that Best Buy used when activating Microsoft 365 Personal.
   • Once signed in, confirm that Microsoft 365 Personal shows as an active subscription.
   • If the subscription is not associated with this account, sign out and try any other personal Microsoft account that might have been used at purchase.
2. Install or reinstall the Microsoft 365 desktop apps from the correct account
   • While still signed in at https://www.office.com with the account that shows the active Microsoft 365 Personal subscription, select Apps and then Install apps.
   • Run the installer and let it complete. This ensures the apps on the PC are tied to the correct subscription and can open all supported files.
3. Make sure the apps are activated
   • Open Word or Excel on the desktop.
   • If prompted to sign in, use the same Microsoft account that shows the active Microsoft 365 Personal subscription.
   • If you see any subscription notice (buy/renew/reactivate), follow the prompts to sign in with the correct account and update the license.
4. Set Microsoft 365 apps as the default for Office file types
   • Right‑click on a Word document (.docx) in File Explorer and select Open with > Choose another app.
   • Select Word (the Microsoft 365 version), check Always use this app to open .docx files, then select OK.
   • Repeat for Excel (.xlsx) and PowerPoint (.pptx) files, choosing Excel and PowerPoint respectively.
   • If an older Office version is installed, uninstall it from Settings > Apps > Installed apps so only Microsoft 365 remains, which prevents older versions from taking over as default.

After these steps, files that require Microsoft 365 should open directly in the installed Microsoft 365 desktop apps, as long as they are supported file types and the subscription remains active.

References:

• Why do I need an account to sign in to Microsoft 365 or Office?
• A subscription notice appears when I open a Microsoft 365 application
• Office 2016 is automatically set as the default application when opening an Office file after installing the Microsoft 365 trial version
• What's the difference between a Microsoft 365 subscription and free web apps
• How to install my 365 accounts on a new computer - Microsoft Q&A
• When opening Word or Excel, getting a 'subscription canceled' message but I have renewed my Office subscription - Microsoft Q&A