PX4 Flow Setup with Pixhawk - need Help

Hello I have problems with setting up the Pixhawk and the PX4Flow Sensor, i connected the sensor via i2c and configured it with QGroundControl both has the newest Update and I got an image to show up when i just connect the PX4Flow. My Problem now is I dont know wich parameter I have to change so my drone fly at a spesific hight and hold the position. I found the option for enable the PX4flow. But if I switch into hold mode my drone says bye and fly just upwards with highest speed, I guess you see wahts my problem is.
Maybe someone can help me if you need more information about my problem just let me know and I try to give you all information you need to help me.

Thanks Marvin