In-game, make sure you are signed into Dovetail Live, then click on the CReators Club button. Any livery or scenario in there you like, click on it, then click the "subscribe" button. Then, whenever you load a route in which it is possible for that livery or scenario to appear, it will automatically. Scenarios under Scenario Editor; liveries in Timetable mode, in Scenario Editor, and spawning randomly on AI trains. If you don't like it, go back to CC, find it, and click "unsubscribe."
So the scenarios I signed up for can I find them without looking for them? Just select the route they refer to? Thanks for the tips.