There are a few different places you need to specify the display name of your WatchKit app.
1. To specify the name of your app in the iPhone Home screen:
In your main iPhone app's Info.plist, set
Bundle display name (see image below).
2. To specify the display name of your app in the Apple Watch app list:
In your main iPhone app's Info.plist, set
Bundle Name (see image below).

3. To specify the name that is displayed when your app is launched on an Apple Watch:
In your WatchKit App's Info.plist, set
Bundle display name:

All the best!
Kevin McNeish
Author of Learn to Code in Swift:
https://itunes.apple.com/us/book/learn-to-code-in-swift/id942956811?mt=11