Currently, trip routes cannot be changed or modified within the app. This is mostly because the route we show doesn't necessarily mean it's the route your navigation app will suggest. Waze or Google Maps may choose a different, efficient route for you to follow. If you use our in-app navigation in the Roadtrippers app rather than another navigation app, the navigation should stay very close to your trip's route.
The best way to modify your route is to go to Roadtrippers.com and create or edit your trip there. You can instructions for customizing your route on the desktop site here: Quickly Customize a Trip's Route
After modifying the route, go to the trip's itinerary then click the Directions button. The directions shown there will be the directions needed to follow your custom route on the map. The directions can be printed or saved as a PDF if your computer supports it.