Hey there LouannFNP,
If you're noticing any trouble with the accuracy of your steps or workouts, calibrating the Apple Watch can help with that. Follow the steps below:
Calibrate your Apple Watch
1. While wearing your Apple Watch, go to a flat, open outdoor area that offers good GPS reception and clear skies.
2. If you have Apple Watch Series 2 or later, you just need your Apple Watch.* If you have Apple Watch Series 1 or earlier, bring your iPhone for GPS. Hold your iPhone in your hand, or wear it on an armband or waistband.
3. Open the Workout app, then tap Outdoor Walk or Outdoor Run. To set a goal before starting, tap
.
4. Walk or run at your normal pace for about 20 minutes.
For additional guidance:
Calibrate your Apple Watch for improved Workout and Activity accuracy - Apple Support
It's also important to note, that it's recommended that the arm that you're using the Apple Watch with should swing naturally. While this applies to exercises, it may also help here to ensure everything is being counted properly. This is mentioned in: Get the most accurate measurements using your Apple Watch - Apple Support
"To make sure that you earn Exercise credit during walks, allow the arm with your Apple Watch to swing naturally. For example, while walking your pet, let the arm with your watch swing freely while the other holds the leash.
If you need both hands while walking, for example to push a stroller, you can still earn Exercise credit with the Workout app. Open the app on your Apple Watch and tap Outdoor Walk. The Activity app relies on arm motion and an accelerometer to track movement, but the Workout app can use the accelerometer, the heart rate sensor, and GPS."
Take care!