How do I install in full detail the magnetic sensor so the GPS Compass

I have a ZTE N817 Quest phone & I'm trying to get the magnetic sensor(s) so that the GPS Compass (as well as any other resources I haven't tried so far) will function; however, I'd need EXTREMELY EXPLICIT instructions on what to do to accomplish this task.

Also, for some reason when I make a call on the phone & wish to end it, I've tried pressing END at the bottom of the screen but that doesn't seem to work. I contacted my customer service area & was told to simply press the lower button on the right side of the phone - why shouldn't the END command on the unit function? Is there some way to enable it?

Another question concerns the sensitivity of the unit: As I'm speaking with the phone against my face, it seems that I'm inadvertently pressing keys so I hear numerous beeps. I was again told to press that same button lightly & that would alleviate the sensitivity. When I tried that, of curse, I disconnected the call so there must be something wrong somewhere!

I'd greatly appreciate someone's help with these issues. Thank you in advance.