To mark a journey as a favorite, tap the yellow star outline.
To remove a journey from your favorites, tap the solid yellow star.
Back Bay -> South Station is not a favorite Back Bay -> South Station is a favorite
About favorite trips
If configured by your transit agency, recently purchased journeys will appear under the Buy Tickets button on the Home screen. They provide a shortcut through the ticket purchasing process. By tapping a journey on the Home screen, you select that route and advance to the Select Ticket Type screen.
By default, the Home screen will display the three most recently purchased journeys. If you want to make sure a journey always appears on the Home screen, mark it as a favorite.