Log in/Register in Menu

Try this code in your functions.php file –

add_filter( 'wp_nav_menu_items', 'sp_add_loginout_link', 10, 2 );
function sp_add_loginout_link( $items, $args ) {
	// Change 'primary' to 'secondary' to put the login link in your secondary nav bar
	if ( $args->theme_location != 'primary' )
		return $items;
	if ( is_user_logged_in() ) {
		$items .= '<li class="menu-item"><a href="'. wp_logout_url() .'">Log Out</a></li>';
	} else {
		$items .= '<li class="menu-item"><a href="'. site_url('wp-login.php') .'">Log In</a></li>';
	}
	return $items;
}

This works for the Primary Menu so you’ll have to make adjustments to the code in order for it to work with the Secondary Menu.

Source – https://gist.github.com/nickcernis/02086c75ee9aa19447e0

I tested on a regular Primary Menu and it worked perfectly for “Logged in” and “Out” users. You can test to see if your adjustments work for the Secondary Menus as well.

Currently, I’m not using any Anti Spam plugins so I’m not sure which one would be best at the moment. I’d check the reviews to see what other users are prefer.

I’ve never done it before, but I did see there are some plugins out there that allow you to customize it. I just Googled “How to customize Dashboard” and a few showed up.