HTC One M8 for Windows - Manual (Page 63)

If you want, give the contact nicknames to make it easy to call that
person.
3. Tap save.
Changing Cortana settings
In Settings, you can turn Cortana on and off, set the name that Cortana will
call you, connect to Facebook, and more.
To change settings, in Cortana tap
> settings.
Cortana 63