It is easy to miss such things I agree. I imagine you aren't the first to not notice it, nor will you be the last.
I've noticed that sometimes when a person wants to adjust a setting that when they look for a way to do it often the solution doesn't present itself easily. I mean depending on the type of browser that a person uses or the release of the same where you click and on what option may not match what instructions are given (in a help dialogue).