Custom Menu in Admin doesn’t change menu in browser

Your menu name doesn’t match in your sidebar. The theme_location should match the name of one of the registered menu’s in your functions.php file.

Try replacing what you have with this:

For the functions.php file:

<?php
add_theme_support( 'menus' );
add_action( 'init', 'my_custom_menus' );
function my_custom_menus() {
  register_nav_menus(
    array(
      'primary' => __( 'primary' ),
      'secondary' => __( 'secondary' )
      )
    );
  }
?>

For the sidebar.php file:

<aside>
  <div class="textBody">
    <div class="sideNav">
      <?php wp_nav_menu( array( 'theme_location' => 'secondary' ) ); ?>
    </div>
  </div>
</aside>