Hello,
1) Niche Market demo version uses a Single product builder ( Theme Options > WooCommerce (Shop) ). In case you activate the builder, the single product page should be created from scratch http://prntscr.com/ptrl3c and then you will get access to new features.
2) “Show Sale Percentage” can be activated in Theme Options > WooCommerce (Shop) > Shop elements > Sale & Out of Stock.
Regards