Hello,
use this code in your wp-admin >> plugins >> plugin editor >> wplms customizer plugin >> customizer.php file.
add_action('wp_footer',function(){
?>
<style>
.dashboard .dash-widget .dash-stats {
display: grid;
grid-template-columns: 60px 1fr;
align-items: center;
}
.dashboard .dash-widget #theImg{margin-left: 25px !important;}
</style>
<script>
jQuery(document).ready(function($){
$('.dash-widget.certificates .dash-stats').prepend('<img id="theImg" src="https://escola.barcovoador.com/wp-content/uploads/2019/08/com-fundo-branco.fw_.png" width="60px"/>');
$('.dash-widget.quizes .dash-stats').prepend('<img id="theImg" src="https://escola.barcovoador.com/wp-content/uploads/2019/08/com-fundo-branco.fw_.png" width="60px"/>');
$('.dash-widget.courses .dash-stats').prepend('<img id="theImg" src="https://escola.barcovoador.com/wp-content/uploads/2019/08/com-fundo-branco.fw_.png" width="60px"/>');
$('.dash-widget.units .dash-stats').prepend('<img id="theImg" src="https://escola.barcovoador.com/wp-content/uploads/2019/08/com-fundo-branco.fw_.png" width="60px"/>');
$('.dash-widget.students .dash-stats').prepend('<img id="theImg" src="https://escola.barcovoador.com/wp-content/uploads/2019/08/com-fundo-branco.fw_.png" width="60px"/>');
$('.dash-widget.badges .dash-stats').prepend('<img id="theImg" src="https://escola.barcovoador.com/wp-content/uploads/2019/08/com-fundo-branco.fw_.png" width="60px"/>');
});
</script>
<?php
});
refer:
http://prntscr.com/owvhcn
Note: change your image url in code. first upload images in media folder then copy and paste the url.