How do you change Word 2016's Display language?
What step or trick am I missing?
You need to install the language pack.
Click Here
Navigate to the list of languages, which by default, has
Which language do you need?written in it.
Install whichever language accessory pack you just downloaded.
Once the language is installed, within the Office Language Preferences, configure the display language you desire.
- In order for the changes to take effect, you need to restart all Office programs
It might be worth pointing out that, while the language appears to be grayed out, you can actually click on it.
Earlier versions of Office had downloadable Language packs but I can't find one for Office 2016, not even in the volume license downloads.
According to the article I found, they should exist, provided you have the appropriate volume license.
If you're an administrator who has deployed a volume licensed version of Office 2016 to your users, you can download an ISO image of the language packs, language interface packs, and proofing tools from the Volume Licensing Service Center (VLSC).
Sources:
Language Accessory Pack for Office
Add an editing language or set language preferences in Office
Language Accessory Pack - Spanish 32-bit
Language Accessory Pack - Spanish 64-bit