I obtained an "Umweltplakette" sticker abroad, and the instructions asked to place the sticker to the top-right or bottom-right corner of the car's windshield (viewed from the driver's perspective). I placed it to the top corner, since it obscures less the driver's view.
However then I learned that the German instructions explicitly ask to place it to the bottom corner:
Is this a problem? Can I be fined because of that?