The Heart Rate Zones are fixed and they are not editable. 
The Heart rate zones are calculated based on your maximum heart rate.
Peak performance 
90 -100% Improves your short high intensity performance
Anaerobic intensive 
80 - 90% Develops your anaerobic high intensity performance
Aerobic fitness 
70 - 80% Enhances aerobic fitness and cardiovascular performance
Fat burn and endurance
60 - 70% Develops aerobic  endurance and increases fat metabolism
Warmup and Recovery
50–60%  Gets your body ready for exercise and accelerates your recovery
 iPhone app only!
You can enable Voice feedback to notify you when you are crossing HR zone lines. 
 
        
      