Throttle runaway

Have a hex with 6, 950kv’s, 4s batt My esc’s have been programed. Throttle rev. . And the esc’s respond accordingly when run without Ardupilot.
When I connect back to Ardu, after arming it only takes slight throttle to make them really wind-up. Then from there they seem to continue to accelerate further. I am at a loss. I know I must be issing something but I think I need a Little help.
Help Please

Have you done a throttle calibration on your ESC, and also radio calibration via APM mission planner?

Have exactly the same issue on 2.9.1b. But when I start flying, throttle is controllable. Motors are starting immediately with like 25% of the throttle, even tho my TX is barely reaching 4-5%. Wondering about this too.

The default setting is “if the motors are spinning they should spin as fast as possible but still safely stay on ground”.
The reason is when descending fast the force of rushing air wants to reverse the rotation of props.
This force can stop the weak driven props from spinning correctly/fast enough, thus a safety mode in some ESC’s kick in and shut engines off to prevent a burn out.

This can be tweaked with the values in parameters setting menus.
For instance if your copter is over powered you must lower this value.
It’s also a good time to also set “mid stick” setting to a lower value so the copter doesn’t suddenly ascend/descend when changing flight modes.

Does this make sense in light of your question?