I barely hear the person i am talking to is there a way to turn up the volume on the phone

Bad Speaker? That's what mine did when the speaker was bad. Try Speakerphone, seriously, then update me!

Have your earpiece retested on another device if you have. If issue occurs on another phone w/ the same earpiece, then you're gonna need to buy another earpiece and if the problem only occurs w/ your device then I suggest you do a master reset.

maybe by mistake you reduce the volume on the iphone.

try the following during a call press on the right control up volume to see if that improve your sound.

if that doesn't work you should go to an apple store or your cell provider.

Whilst on a call in bluetooth mode change the volume. It needs to be for each different "speaker" you use

this phone has many different volumes to play with, one of them is the volume for, when your calling someone, simply, when you call someone, press the volume up button, and you should hear the person louder

Seems your ear speaker has a problem. It need to be changed.

how to down load mxit?

I had the same problem with that phone... while manipulating the mobile part (cover) you can slightly improve the volume.
Another point to check is the button on the side of the phone which allows to increase or lower the volume: it could happen that you turn the volume low without noticing it...
My solution was to replace the phone.

if you have tried raising the volume while on a call and you still have the same trouble then I'm afraid your earpiece has failed and you will need to take it to a tech and have the earpiece replaced

I think your signal amplifier has a problem. If this is a new phone return it for a replacement.