wappaloochie,
The 'full screening' you experienced is not a feature of the app, but of Windows. When loading Windows 8.1 apps on Windows 10, Windows will always include the full screen button on the title bar, just to the left of minimize, which is what you clicked to get into the full screen view. When you go into this full screen mode, hovering near where the title bar would be brings the title bar down so that full screen mode can be exited.
Again, this is not a feature of our app, but is a Windows feature for legacy applications on Windows 10. The new Gospel Library for Windows 10, currently in open beta, does not have the full screening button as it was built for Windows 10. You can learn more about the beta at the link below:
https://tech.lds.org/wiki/Gospel_Library_for_Windows_10