I would likely turn the water in the world into a sweet variation of itself, making it Soda, Bubbly Water, or Juice. Just to see how much would it would take for humanity to adjust towards this newly given dilemma. Considering the power states turn anything [any matter] into a sugary sweet and I feel like I would figure out how far this power stretches out. Placing my hands on the ground in hopes of transmutating it to a doughy substance.
Possibly expanding across the miles as I have now changed every floor to be walked on into a doughy substance that can be consumable. Overall using this power to fuck with humanity itself and see how they'd adapt to a sugary world.