The 64-bit version is installed by default, microsoft365.com/setupunless Office detects that you already have a 32-bit version of Office (or a stand-alone Office application such as Project or Visio) installed. In this case, the 32-bit version of Office will be installed instead. To switch from a 32-bit version to a 64-bit version or vice versa, you must first uninstall Office, including any stand-alone Office applications you own, such as Project of Visio. When the uninstallation is complete, log back on to Select More installation options, choose the language and version you want (64 or 32 bit), and then Select Install. If you want to buy Microsoft 365, you need to follow these simple steps: Go to Microsoft365.com. Choose For Home, For Business, For Business, and For Education. Select your plan and click Buy Now. Log in to your account or create a new one.