PlayStation Using Trains On Other Routes

Trying to design a scenario and the option to add trains not native to that route, is not appearing?

I've done it before - I've added and used German locos on isle of wight ; and now it is only showing I can create scenarios with the 483?!

Why has this option been removed ? How can I restore it ?

 

Did you select off the rails mode?

 

No how do i do that ? Sorry I should have looked more closer

 

Nevermind I've found it thankyou, had to go to scenario details