Alter The "bars" icon In The Mobile Menu Link

function my_mobile_menu_open_button_icon( $return ) {
   return '<i class="YOUR CUSTOM ICON"></i>';
}
add_filter( 'ocean_mobile_menu_navbar_open_icon', 'my_mobile_menu_open_button_icon' );

All PHP snippets should be added via a child theme's functions.php file.