Sorry, but it's now time for me to admit....I've got no idea what you mean by a "horizontal " route...
On 3D view, you have a fixed car icon at the bottom of the screen and your route always goes up towards the top of the screen (assuming you are currently driving on a straight road)
On 2D view, it depends on your model, you either get the option of "North up" or "Direction up", or on the simpler models you only get "North up".
In 2D "North up" the display looks like the "Browse map" overhead view with the car cursor wiggling around on the road as it goes along. So if you were travelling east-west it would be going horizontally, but if you were going north-south it'd be moving vertically.
Sorry if I'm not grasping what you mean, but the "broad roads/ narrow roads" description has me confused too!
Any chance you could take a photo of the screen that shows what you're seeing and post it here? (Even better you can make screen grabs directly on the TomTom - some instructions
HERE ) - but don't worry if that's too much hassle, any old photo will do.