everyone says they can barely hear me

OK when the phone says HD on in notifications double click it then press info then double click it again and force stop it everything works fine for me now

I was having this problem as well. I checked the microphone with a flashlight (which is the small whole that's at the bottom of the phone, next to the USB port), and I noticed that there was some crap in it. I used a needle and removed it, and that did the trick. People can hear me perfectly now. BUT BE CAREFUL NOT TO GO TOO DEEP WITH THE NEEDLE, you might damage the microphone.

The mic could need to be replaced. More likely than not its a hardware issue with the phone. How long did it work before it started ? And does it always happen now or sometimes not?

"Speak into the holes at the top and bottom of phone that's where your mic is. Or clean the area where the holes are they tend to get clogged with dust

Update (07/29/2017)

Microphone are the holes at the top and bottom of the phone they tend to get clogged with dust. You may use a small pen needle or blow air into the holes. This actually work with my phone which is a ZTE XL."

My friend had been having trouble for months. Today he determined that the mic is on the back so you have to hold the palm of your hand over the screen instead of the back.