[Brian]

Esther, thanks for trying OmniPlan. Happy to help! At the top-right of the Gantt view, you'll see a magnifying glass icon with a plus sign in the lens. Clicking that brings up a menu where you can set the time scale.

Thanks for mentioning this - I did a couple of help searches and failed to turn up the documentation on that. Filing that as a bug. Sorry for the trouble it caused!