The Menu button can be activated by pressing your Menu button on the device you have, but as I can see, the software doesn't really have a dedicated menu to configure options. You just select New and then use the small guide and that's it. Additionally, click the only button in the middle located on the right side of the application.
Try pressing the Menu on your device and the inside menu should appear. If there isn't one, then the Pro version lacks it or it could be an issue with the software as well.
If you actually believe this is a bug, report it to the developer: lotuzstudio@gmail.com