General help using QGC and Aedupilot

I need help wit ESC calibration using QGC 3.4.4. I have flashed my 400mm copter with Ardupilot using a Pixhawk 2.4.8 flight controller. The power screen that shows is different to the one shown in the documentation and I can’t get the calibrate part to show. My guess is that I have missed which box to click to activate this function.