Hmmm, very strange.
I've got no problems whatsoever. Previous and Next buttons work.
Both in overlay mode 1 and also without overlay.
The only thing which is annoying, is the keyboard shortcut. [Y] apparently meanwhile is the default key for "previous", which used to be [Z] in the past and which is in conflict with the about-information, which also still mentions [Z] for "previous"!
PS: Congrats and enjoy school!!