How to exit a preview on Android XD?

So, I feel super stupid. But I just created my first prototype in Experience Design on my Mac, uploaded the single artboard with shapes, colors and text to Creative Cloud and opened it on my Android phone using XD. But I can't seem to find out how to close it. Using the android "back button" sends me to my Android launcher/"desktop", and there are no other menu buttons. No options on swipe left or right, up or down (no other artboards). Closing the app and restarting it send me directly to the preview again, no choice to select different projects to preview. What am I missing??