Hi @bestglide -
This question has been answered many times! The best current advice depends on if you’re using QGC or Cockpit. If you’re just using ArduSub (4.5.3 or earlier) , you can also control the outputs on channel 9, 10 and 11 via buttons as if they are servo outputs, just like it was a gripper. You may have to increment the output signal to 1500 microseconds before the ESC initializes in this way - which is also necessary if you configure it as a lights output.
Perhaps it is best summarized here?
In any case - changes are in the works, as Eliot describes here to make this all much simpler to explain, and more intuitive to setup!