change front end menu depending on user login

Define two menus and serve them based on if they are logged in or not which you can do in your theme’s functions.php file:

if (is_user_logged_in()){
  wp_nav_menu( array(
    'menu'            => 'Logged In Menu',
    'container_class' => 'logged-in-menu',
    'theme_location'  => 'logged-in'
  ));
} else {
  wp_nav_menu( array(
    'menu'            => 'Visitor Menu',
    'container_class' => 'visitor-menu',
    'theme_location'  => 'visitor'
  ));
};

You’ll also need to register their theme locations which you can do in your theme’s functions.php file as well:

register_nav_menus( array(
  'logged-in'  => __( 'Logged-in Menu Area',  'yourtheme' ),
  'visitor' => __( 'Visitor Menu Area', 'yourtheme' ),
));

And you’ll have to assign those menus to their menu locations in the admin, like so: