resolution issue

A developer sold us a “game” created with Unity. It worked fine for a few years. Now it boots up with a new resolution that stretches horizontally beyond the sides of the display. Is it obvious to anyone what changed here? Can’t I just roll some config file back to an earlier version?

The Alt key finally got the res dialog to come up. Thanks for the clues. We might even buy this and get all schooled up on it. Thanks again, it’s nice that there is a community when the sellers have left the premises.