How can I change the appearance of the buildings?

First, find the object whose design you wish to change, then follow these steps:

• Tap and hold on the object for 3 seconds
• Wait for the pop-up with 3 design options
• Select the option you want and confirm your choice by tapping the tick button

You can do this for an object as many times as you like, but you will need to spend coins to unlock new design options. Once a design option is unlocked, you can switch to it at any time at no cost. Note that not all objects can have their design changed.