I want to change the haptic ‘walk’. It never records the amount of exercise I do

you probably right, i also noticed several times that if i walk slowly, watch does not count.

i also found this:

According to apple support, for the activity ring to register your workout (for outdoor walk or exercise ring) you need to maintain a speed of approx 3.3 mph or faster and increase your heart rate to approx 75% of maximum,this is their definition of a "brisk walk"

since it's from discussions too i don't know if numbers are correct, but anyway there is a minimum definatelly

To earn 1 minute of exercise credit(green ring);

Travel a full minute at a brisk walking pace 3.3 mph or 18 minutes per mile approx.

or

5.3kph or 11.3 minutes per kilometer.

Raise your heart rate to approx 75% of your maximum.

When you're at around or above this heart rate and speed for the entire minute you'll receive 1 exercise minute credit.

If you pause or slow down during this minute then you won't get any exercise credit for that minute.

Source;phone call I had with apple support.

do you mean auto-start does not work or something else?

what apple watch model do you have?