HTC One M8 for Windows - Manual (Page 56)

Changing the keyboard language
You can choose between a variety of languages, layouts, and regions for
your keyboard. Your phone can provide word suggestions and spelling
corrections based on the language you choose.
1. Swipe down from the top edge of the screen with one finger.
2. Tap All settings > keyboard.
3. Tap add keyboards.
4. Select the languages you'd like to be able to use from the onscreen
keyboard. The next time you use the keyboard, you'll see the
language key .
56 Your first week with your new phone