It is there. I found it today. Not sure why I did not see it last night, but I was on a laptop and the screen is smaller.
Anyway here is a pic to display where the arrows are and what they do.
Hope this helps.
And, if no arrows show up (like in the 1st post on the pic below, that means you have read all the posts in that thread. I'm guessing that is why I did not see the arrow last night.