Sometimes it is not possible to close jAlbum, because the 'Save settings' modal window is behind the Explorer window, see screen-shot.
Unfortunately I can't reproduce this, but I have seen it several times.
I use Windows 10 with my Desktop distributed over two monitor screens.
If have the skin settings window is on the left screen and the Explorer window on the right screen, see enclosed screenshot.
If I change now a checkmark in the skin settings on the left screen and next close jAlbum with the close button in the upper right corner of the Explorer window on the right screen, jAlbum hangs, probably with a hidden 'Save settings?' window.
Sorry to hear that. I also think this has to do with window modality. Way back (Java 8), window modality was tight in Java, but since then we've had various issues with managing window modality when there are more than 2 windows involved, especially on Mac. This is probably something we should file a bug report to Oracle about.