How can I get mt watch to count all steps accurately?

See the "Make sure that you earn Move and Exercise credit" section in:

Get the most accurate measurements using your Apple Watch - Apple Support

You should also make sure your watch is calibrated:

Calibrating your Apple Watch for improved Workout and Activity accuracy - Apple Support

Wave your Apple Watch arm while riding any bike.

Strap your Apple Watch to your leg.

Steps are counted based on the accelerometer in the Apple Watch. Holding onto handle bars does not move the Apple Watch in an arm swinging motion typically when walking or running.

It won't count steps for a stationery bike as you aren't taking any steps.