Click the start menu (windows icon at the bottom of the screen)
Type "appwiz.cpl" and click "Open"
A new window will appear, from there, scroll through the list and right click the Microsoft LTSC 2021 (Might be Office 2019, 2016, etc) application and click "Uninstall".
After uninstalling the old version, you MUST restart your machine otherwise the next part will fail.
From there, click the start menu and type "Software Center" and click "Open"
Once it is open, you will see a list of applications to install.
You will click the "Microsoft Office 365 64-bit FacStaff - Install" option, and then click "Install" (Screenshot shows "reinstall", but it should say "install" for you)
After that is finished, the "cancel" button will say "reinstall" and that's how you know its complete. Do not click the reinstall button, and you should be able to open word, excel, powerpoint, etc...