Bidirectional Lines?

I am probably missing something/just dumb but I simply cannot figure this out.

When I build a line using parallel tracks, I can build a route going one way no problem (starting at end station “A” and going all the way to end station “B”).

However, when I try to create another route for the line to go the opposite direction (from station “B” all the way to station “A”), no matter what I do, the numbers always switch up such that the first station ends up being A and the route ends up going in the exact same direction. I basically cannot get the new route to start at B and go to A. What am I doing wrong?