Arducopter Heli V3.4.6 setting Alt Hold question

Thank in advance for any help
Pixhawk, Arducopter Heli V3.4.6, Trex 450, Tarot FBL head, ER9X,
In Arducopter Heli 3.4.6 alt hold is called self learning, I have read online that this is not true for Helicopters just multi rotors, and for helicopter has to be done with the Stabilize 4 point parameters? Am I understanding this correctly? What is the proper process to set Alt Hold with a helicopter and Arducopter V3.4.6.
I have turned down Accel Z P to 0.2, no more up and down osculating, my heli seems to somewhat preform alt hold but is far from ideal?

William, you can adjust the IM_STAB_COL values to get the helicopter to hover at mid-stick in Stabilize, so that when you switch to Alt Hold the helicopter doesn’t suddenly go up or down. There is no real “tuning” for Alt Hold. If it doesn’t hold altitude very well, look at your Z-axis vibration levels. Anything over about 20 will cause the altitude to jump around in the altitude controlled flight modes.