Selecting road options on Navigation

Recently we were in LA and wanted to drive on surface roads, as opposed to the freeways. We opted out if interstates on the screen that lets you select your options but the Nav Nazi refused to cooperate and kept trying to route us so as to use the freeway. A couple of times our destination was straight ahead on the road we were on but we kept being nagged to drive out of the way so as to be on a freeway.
I need to be enlightened as to what I am doing wrong or doesn't it actually accept input from this screen? Hmm, maybe I was moving every time I chose to avoid freeways. Could that be it? Thanks for your help.