To change the order of your slides, hover over the slide, and then using the icon in the top right corner, drag and drop it into the new position.

You can also re-order slides in the editor by grabbing the empty area on the left:

Components

To swap a component with a different one within the same slide, hover over one and simply drag and drop it into the desired position. You can swap images and even text blocks.

Components can also be dragged and rearranged in the editor. These components can be rearranged within the current slide or even moved to a different slide. 

To move a component onto a different slide, click and drag the component's setting menu in the editor.