Functions.php change for Woocommerce not working

It’s possible the theme or another plugin are using that hook with a later priority. Your add_action would have the default of 10; try giving it a 12 or a 20, etc. and see if the text shows up.

add_action('woocommerce_before_add_to_cart_form','print_something_below_short_description', 10);

You can read about Priority with Action Hooks here.