1. Start Creator with empty settings.
2. Go to "Tools" -> "Options..." -> "Build & Run" -> "Kits".
   There should be one kit named "Desktop" which is the default.
3. Select kit "Desktop".
4. Click the "Clone" button twice.
   By this you clone the default kit and then clone the clone:
5. Click "OK".
6. Go to "Tools" -> "Options..." -> "Build & Run" -> "Kits" again.
   You see the three kits sorted alphabetically:
   
7. Select kit "Clone of Clone of Desktop".
8. Click "Make Default".
9. Select kit "Desktop".
10. Click "Remove".
    So far, everything looks right:
    
11. Click "Apply".
    The default kit changes to "Clone of Desktop"

When a default kit is set manually, clicking "Apply" should never change this.