My iPhone 5s crashes a lot!!!

Hello there,

Why is my iPhone 5s crashing a lot with almost every app I use even sometimes when I open Settings? I like the phone so far other than this very annoying issue. This is my 2nd device after returning the 1st one because of the same problem plus and issue with the microphone that seemed to be over heated after a long period of phone call, and maybe this device will end up to be returned too. I've done hard reset/soft reset many times and even tried to restore as new (from scratch) but nothing really has changed. I enabled the automatically send for diagnostics and usage so that Apple might notice the crazy reports I get from crashing. Please I need help as soon as possible.

Best,

Adel