RCn vs Servo_n for servo control

I am a bit confused about the difference between RCn and servo_n. I read that RC is the input and servo is the output but I don’t understand why they would be different and when we would modify one and not the other? I am trying to control a continuous rotation servo using Aux channel 2. The servo has a pwm range between 800 and 2100. I changed the servo10 min and max to 800 and 2100 respectively. I also tried a few different values for the servo10 trim but didn’t see much difference in results for the different values. When I turn the rov on, the servo starts rotating automatically and I have to use joystick input to decrease the servo pwm until it stops. Isn’t trim the value that is output on that channel when the rov first turns on? If so, it should be affecting the motion of the servo at startup but I don’t see that. Please let me know if I am going about this the correct way and whether RCn parameters have something to do with this as well