How do I prevent false fall alarms on Apple Watch?

You’ll want to discuss what is happening here with Apple Support, particularly if this is a new Watch, or if the activity does not appear to warrant fall detection teiggering:

Contact Apple Support - Apple Support

I know of a few activities that are fairly reliable at generating a false fall, but the details here matter.

Use Fall Detection with Apple Watch - Apple Support

As Apple puts it: “Apple Watch cannot detect all falls. Your watch might detect high-impact activity as a fall and trigger Fall Detection.”

Is your fall alarm only on during workouts (when you're not old) or always on? If you cannot tick I didn't fall you might want to get this up with apple because there can be a bug going on

SDKeeffe wrote:

It sent out a false alert, no response when I tapped on “ I didn’t Fall” repeatedly and it continued to send out multiple alerts over and over! I finally turned the fall notification off and turned off both phone and watch to get it to stop sending out alerts.

That’s best a discussion with Apple.