How to change the UI language for Office 365 for Mac OS X when it’s stuck

THE PROBLEM: I finally took the plunge and subscribed to Office 365. Once installed, I noticed all the User Interface (UI) was in Japanese. There was no setting in each Office applications’ Preferences and also made sure that US English was chosen in OS X’s System Preferences > Language & Region > General. I had used the Japanese setting before, so I made sure to delete that from the list and restart the computer. I even deleted my Japanese input method from the Keyboard Preference pane. To no avail, Word, Excel, and Powerpoint UIs were stuck in Japanese.

THE CAUSE: If you’re a long time Mac user like me, you have probably migrated an old OS X account from computer to computer – preserving the users’ preferences through many versions of Microsoft Office. And if you’ve worked for a foreign company, you probably have installed a non-native language version of Office once before but uninstalled it since then. Your computer might have been setup by the company IT in a foreign language, then your account was created in English. In scenarios like this, “smart” installers like the one for Office 365 for Mac might picked up the scent of the foreign language files and presented you Word, Excel, and PowerPoint in that foreign language.

THE SOLUTION: You can fix this by forcing the individual application to re-remember (or forget) it’s UI language.

1. Open System Preferences > Language & Region > Apps pane
2. If Word/Excel/Powerpoint is not listed, click the “+” button to add it.
3. From the dropdown list, choose the language it’s currently showing (in my case, Japanese). Keep System Preferences open.
4. Open the application, then Quit it.
5. With the application closed, now choose the language you want (in my case, US English)
6. When you open the application again, it should be in the language you want it to be in.
7. One step further: If you’ve chosen the same language as the System’s default language, you may delete the entry from the list using the “-” button.

This is a much safer solution than to delete the lproj folders from the Contents of the application or executing Terminal commands against the plist files.