Font Awesome 5 uses svg for icons and path inside are set with fill:currentColor so simply change color of svg:
.icons svg {
color:#2759AE;
}<script defer src="https://use.fontawesome.com/releases/v5.5.0/js/all.js"></script>
<div class="container mt200 icons">
<div class="col-md-3">
<div class="bggray2 text-center">
<i class="fas fa-microphone fa-5x"></i>
<div class="title">LOREM</div>
<div class="text">Vestibulum ac diam sit amet quam vehicula elementum sed sit amet dui.</div>
</div>
</div>
<div class="col-md-3">
<div class="bggray2 text-center">
<i class="far fa-edit fa-5x"></i>
<div class="title">LOREM</div>
<div class="text">Vestibulum ac diam sit amet quam vehicula elementum sed sit amet dui.
</div>
</div>
</div>
</div>As you can see in the code, the i are replaced with svg when you load the JS version:
You can apply color to i in case you are using the CSS version.
.icons i {
color:#2759AE;
}<link href="https://use.fontawesome.com/releases/v5.8.1/css/all.css" rel="stylesheet"><div class="container mt200 icons">
<div class="col-md-3">
<div class="bggray2 text-center">
<i class="fas fa-microphone fa-5x"></i>
<div class="title">LOREM</div>
<div class="text">Vestibulum ac diam sit amet quam vehicula elementum sed sit amet dui.</div>
</div>
</div>
<div class="col-md-3">
<div class="bggray2 text-center">
<i class="far fa-edit fa-5x"></i>
<div class="title">LOREM</div>
<div class="text">Vestibulum ac diam sit amet quam vehicula elementum sed sit amet dui.
</div>
</div>
</div>
</div>So to make sure it will work in all the cases simply use both selector:
.icons i,
.icons svg {
color: #2759AE;
}