Save custom route

[shanepardue]

I know this has been asked a few times, but I'm having a hard time finding a good solution to my problem.

I am finding that occasionally my TomTom One XL S is telling me to take a longer route than I should and I would like to designate the correct route. I've heard it said to create an itinerary, but would that also require an itinerary for the return?

Is there any chance I could save a route the TomTom thinks is an alternative as the default?

Thanks for your help. This is my first GPS unit and I can't wait to get comfortable with it!