I'm sorry to hear that! For the inventory arrows you can try dragging up and down wherever the menu's empty (that may be hard to do on mobile). Alternatively, if you're on PC, you can use the mouse scroll wheel.
We'll be looking into getting recordings and screenshots ASAP to help anyone else with bugs!
Hi! One of the devs here. I noticed that the game ran pretty slow on my phone as well (Samsung note 5). We'll definitely have to do some optimization to get the game running faster, sorry about that! As the for the inventory arrows, I never actually hooked them up so they don't work... But you can scroll the box by placing an item on the crafting board and swiping on that spot (haha). We'll get this all fixed soon!
