Everything appears on screen as expected, except that the image linked to the first slide in my carousel (the active carousel-item) is the only image that appears on my web app when I reload it. When I click the next/prev buttons, nothing happens except I am returned to the beginning of the div containing the entire carousel (in my code, it's id is #carouselExampleIndicators).
The carousel code below was copied and pasted from this Bootstrap page (only edited the src values to link to an image on my computer) and the link/script tags to retrieve Bootstrap 4.3 were copied and pasted from this Bootstrap page (under Bootstrap CDN).
<!-- Bootstrap CSS -->
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css" integrity="sha384-ggOyR0iXCbMQv3Xipma34MD+dH/1fQ784/j6cY/iJTQUOhcWr7x9JvoRxT2MZw1T" crossorigin="anonymous">
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/js/bootstrap.min.js" integrity="sha384-JjSmVgyd0p3pXB1rRibZUAYoIIy6OrQ6VrjIEaFf/nJGzIxFDsf4x0xIM+B07jRM" crossorigin="anonymous"></script>
<!-- Carousel -->
<div id="carouselExampleIndicators" class="carousel slide" data-ride="carousel">
<ol class="carousel-indicators">
<li data-target="#carouselExampleIndicators" data-slide-to="0" class="active"></li>
<li data-target="#carouselExampleIndicators" data-slide-to="1"></li>
<li data-target="#carouselExampleIndicators" data-slide-to="2"></li>
</ol>
<div class="carousel-inner" role="listbox">
<div class="carousel-item active">
<img src="img/IMG_9840.JPG" class="d-block w-100" alt="First Slide">
<div class="carousel-caption">
<h3>1st Pic</h3>
</div>
</div>
<div class="carousel-item">
<img src="img/IMG_9834.JPG" class="d-block w-100" alt="Second Slide">
<div class="carousel-caption">
<h3>2nd Pic</h3>
</div>
</div>
<div class="carousel-item">
<img src="img/IMG_9836.JPG" class="d-block w-100" alt="Third Slide">
<div class="carousel-caption">
<h3>3rd Pic</h3>
</div>
</div>
</div>
<a class="carousel-control-prev" href="#carouselExampleIndicators" role="button" data-slide="prev">
<span class="carousel-control-prev-icon" aria-hidden="true"></span>
<span class="sr-only">Previous</span>
</a>
<a class="carousel-control-next" href="#carouselExampleIndicators" role="button" data-slide="next">
<span class="carousel-control-next-icon" aria-hidden="true"></span>
<span class="sr-only">Next</span>
</a>
<!-- jQuery first, then Bootstrap JS. -->
<script src="https://code.jquery.com/jquery-3.3.1.slim.min.js" integrity="sha384-q8i/X+965DzO0rT7abK41JStQIAqVgRVzpbzo5smXKp4YfRvH+8abtTE1Pi6jizo" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.7/umd/popper.min.js" integrity="sha384-UO2eT0CpHqdSJQ6hJty5KVphtPhzWj9WO1clHTMGa3JDZwrnQq4sF86dIHNDz0W1" crossorigin="anonymous"></script>