Help with Setting up Sonar HC-SR04 3 wire on a APM 2.6

Thanks to anyone in advance for help.
I have a APM 2.6, Ver 3.2.1 and trying to set up 3 wire sonar HC-SR04 module.
I know this subject has more than likely been discussed before, but I cannot find any actual setup details? I have tried to follow these instructions from Utube (Cheerson cx20 Apm 2.8 and v252 v5.0 Sonar mod hc-sr04) but sonar readings never change? Don’t know if it is working or not?
Can someone tell me or direct me to instructions to setup this sonar?
Thanks to all