Oh I have the same problem with the blooming things! Up and down, up and down, like a tart's knickers, and never at the position one wants.

My sister was on the phone yesterday - she's trading in her year-old Focus for yet another all-singing all-dancing affair. Even she says the computer screen thing is no use as she wears glasses for seeing long-distance, and needs to change them for her reading ones to see the screen (too dangerous to do that en route)
I reckon she likes to cut a dash and impress her friends, the show-off!