Button showing wrong text

I added this plugin and all worked correctly. Then I experimented by adding the shopping cart shortcode to my page. I removed it, but now the only button I have available says ‘Add to cart’ instead of ‘PayPal’. I want to go back to the PayPal label.

I have tried uninstalling the plugin, but it remembers all my details when I re-install it.

The page I need help with: [log in to see the link]