Watch Alarm ONLY vs Phone

I have a sleep schedule set up to wake me up at 6am M-F.

When I am sleeping near my phone (which is on it's charger) my watch alarm goes off every day, no problem.

However, often I end up in one of my children's beds in the middle of the night and the alarm will then go off on my phone only (which I am not near) and not my watch.

How can this be changed so that my alarm goes off on my watch ALWAYS & ONLY?