Visibility/Opacity changes 2 one slide change all slides - how to undo?

Was working with the sliders (visibility & opacity) for one foto. Shut down the software & OS. Opened FM & saw all slides had now “disappeared.” They are still shown as being used.

How can I revert to having all slides visible?


Can you please upload a screen shot (command-shift-4) so we can see how this looks like?