There was just a question about this in the last week so you are not alone. I’m going to dig for you since I think it had at least the cause and perhaps the solution.

Edit: http://www.fluther.com/167864/how-to-get-the-up-and-down-scrolling-arrows-back-on/

Not sure if that really helps. But at least you are not alone and that can be comforting.

Here is an explanation and a workaround.

It is frustrating that they didn’t just make it a setting. Sure, most people haven’t used those arrows in years. But you should have the option to.