e 64-bit version is installed by default, unless 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.