It’s sometime confusing for new developers (or rather new Watch iOS developers) to find exactly where to set the Watch Icons. Well… it’s actually pretty simple.
It may be a bit unclear, because if you use a standard XCode template App, you may find two Assets.xcassets. The first would be under the WatchKit App and the second one under the Watch Kit Extension, usually where you insert your code logic.
Well, check out the Assets.xcassets under the WatchKit App group-folder, that’s the one. You will find in this image assets the AppIcon group, fill the icons and you are good to go.
Caveat: Do not try to create the AppIcon group in the WatchApp WatchKit Extension Assets.xcassets, it won’t work… That’s a rookie mistake.