Changing H1 font-family in bootstrap 4 - html

Question

So I was wondering how to change the H1 font-family in Bootstrap 4? Can't seem to get it right.. I'm kind of new to this bootstrap thing, so I followed a tutorial on Youtube, but they didn't explain how to change the font-family..
See the code here: (I deleted my css, because it didn't work at all and I honestly didn't even know what I was doing)
<div class="container">
<h1 class="display-2">Hello, World!</h1>
<p class="lead">This is a paragraph, you can say a lot of things in here!.</p>
</div>
FULL CODE:
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
<link rel="stylesheet" href="stylesheet.css">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/css/bootstrap.min.css" integrity="sha384-PsH8R72JQ3SOdhVi3uxftmaW6Vc51MKb0q5P2rRUpPvrszuE4W1povHYgTpBfshb" crossorigin="anonymous">
<nav class="navbar navbar-expand-sm navbar-light bg-info">
<button class="navbar-toggler" data-toggle="collapse" data-target="#mainNav">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse" id="mainNav">
<div class="navbar-nav">
<a class="nav-item nav-link active" href="index.html">Home</a>
<a class="nav-item nav-link" href="about.html">About</a>
<a class="nav-item nav-link" href="port.html">Work</a>
<a class="nav-item nav-link" href="contact.html">Contact</a>
</div>
</div>
</nav>
<div class="jumbotron jumbotron-fluid bg-info text-white text-center" style="background: #aaa">
<div class="container">
<h1 class="display-2">Hello, World!</h1>
<p class="lead">This is a paragraph, you can put text in me.</p>
</div>
</div>
<script src="https://code.jquery.com/jquery-3.2.1.slim.min.js" integrity="sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.3/umd/popper.min.js" integrity="sha384-vFJXuSJphROIrBnz7yo7oB41mKfc8JzQZiCq4NCceLEaO4IHwicKwpJf9c9IpFgh" crossorigin="anonymous"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/js/bootstrap.min.js" integrity="sha384-alpBpkh1PFOepccYVYDB4do5UnbKysX5WZXm3XxPqe5iKTfUKjNkCk9SaVuEZflJ" crossorigin="anonymous"></script>

Answer 1

You are loading the style sheets in the wrong order - first needs to be the Bootstrap css and then yours (assuming that stylesheet.css is where you are setting the alternate font-family on the h1) - so that your can overwrite the BS styles- AFTER loading bootstrap. The following shows the order the stylesheets should be loaded :
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/css/bootstrap.min.css" integrity="sha384-PsH8R72JQ3SOdhVi3uxftmaW6Vc51MKb0q5P2rRUpPvrszuE4W1povHYgTpBfshb" crossorigin="anonymous">
<link rel="stylesheet" href="stylesheet.css">
As a demo of the alternate font family:
The following shows 2 h1's - and I am loading in an alternate font family
.alternate-font {
font-family:"Montserrat"
}
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/css/bootstrap.min.css" integrity="sha384-PsH8R72JQ3SOdhVi3uxftmaW6Vc51MKb0q5P2rRUpPvrszuE4W1povHYgTpBfshb" crossorigin="anonymous">
<link href="https://fonts.googleapis.com/css?family=Montserrat:300,400,500,600" rel="stylesheet">-
<h1>This is a h1 using standard bootstrap h1 font-family</h1>
<h1 class="alternate-font">This is a h1 using Montserrat font-family</h1>
<script src="https://code.jquery.com/jquery-3.2.1.slim.min.js" integrity="sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.3/umd/popper.min.js" integrity="sha384-vFJXuSJphROIrBnz7yo7oB41mKfc8JzQZiCq4NCceLEaO4IHwicKwpJf9c9IpFgh" crossorigin="anonymous"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/js/bootstrap.min.js" integrity="sha384-alpBpkh1PFOepccYVYDB4do5UnbKysX5WZXm3XxPqe5iKTfUKjNkCk9SaVuEZflJ" crossorigin="anonymous"></script>