[mnemonicj]

I am not sure if you are supposed to be able to adjust them horizontally. My previous car's manufacturer (Nissan) had a recall for my 2001 Sentra because they forgot to put the tamper-proof cap on the horizontal adjustment. So maybe you can adjust them, but you might have to break a piece to be able to do so.

URL to the Recall: Enter 2001 Nissan Sentra
http://www.nissanusa.com/form/0,,action-NRecallPublicLanding_sctid-51054,00.html#22356