This script doesn't unlock any of the site themes. It only changes the theme you see. You can change your theme by going to your preferences (http://www.neopets.com/preferences.phtml) and changing it there. As soon as you pick a theme, it will change immediately so feel free to surf Neopets with your new theme. There's no need to press 'Change Your Details'. If you press the button, either by accident or because you're changing one of the other site preferences, don't worry. Neopets will only think that you've changed your site theme to 'Neopets Basic'.