I'm just trying to swap an engine! Pffffttttt!

OK, so all nerds aren't Geniuses.
I got the great Montour route last night and I love it. BUT, all I have is two free roams, one of them the engine (a switcher) is a "ghost" image, seems I don't have it? So, I tried on the TS screen to change the engine. The button says "change" under the engine and the route. Should be easy, right? Ummmm, no. Change the engine, and the route changes! No, not what I want. I want an engine I own on the Montour.
I had RW Tools a year ago but lost it in a format of Win 7, do I need it back to do this? Thought TS2014 was supposed to make this easier. I looked at the "build" menu but I'm lost. I know this is a simple task for most of y'all, I just don't get it. HELP!

I had RW Tools a year ago but lost it in a format of Win 7, do I need it back to do this? Thought TS2014 was supposed to make this easier. I looked at the "build" menu but I'm lost. I know this is a simple task for most of y'all, I just don't get it. HELP!