For setting sunrise/sunset times on the outdoor watchface of your Spartan, you need to activate the GPS as sunrise/sunset parameters are based on your location.
How to activate GPS on your Spartan:
1. Go outside
2. Open the Navigation settings
3. Select Your location. When the coordinates appear, your watch has a GPS fix.
4. Cancel saving your location.
5. Go back to the watchface. The sunrise/sunset times should be updated with actual values, if the GPS activation was successful.
Learn more about how to set sunrise and sunset alarms in the user guide of your Spartan.