Press and hold on the dinosaur paddock, building, or decoration you wish to move in order to enter ‘Park Placement’ mode. In this mode, you can drag the object in question to the location of your choice and then tap on another object to move it to a new location as well. You can continue doing this as many times as you like in order to rearrange your park. When you're all finished with moving items around, simply press the green check mark at the bottom right corner to confirm your changes!