Ship to a different address selected as standard on checkout

You can add this to your theme’s functions.php file.

add_filter( 'woocommerce_ship_to_different_address_checked', '__return_false' );

I would recommend to add any custom PHP code or CSS changes to a child theme. This is to prevent the lost of this customization if the parent theme is ever updated automatically.

If you do not know how to create a child theme in WordPress, please reference this link http://codex.wordpress.org/Child_Themes