How do I customize the dashboard?

Subscribers will see the WP Events and News widget, but they shouldn’t be seeing the other stuff. Somewhere the theme and/or plugins are adding widgets in a way that’s allowing all user levels to see them. You can either hit up the support teams for the themes and plugins that are adding them, or you can create your own plugin with code that removes these metaboxes. You’ll need to look up the name for each meta box; here’s one example that removes the “Right Now” box:

<?php
add_action('wp_dashboard_setup', 'wpse_298944_clear_dash_widgets');
function wpse_298944_clear_dash_widgets() {
     if(!current_user_can(publish_posts)) {
          remove_meta_box('dashboard_right_now', 'dashboard', 'normal');
     }
}
?>

Another option is to call the global variable $wp_meta_boxes and unset them one by one. See How to Remove ALL Widgets from Dashboard?