text editing and enhancement

I never know when I reply to a thread if I'm going to find editing buttons above the reply box or not. Tonight, it's very not. Nada. Does anyone else have this problem?

I'm talking about the box of icons I am occasionally delighted to find that allow you to use bold or italics, add photos, links, quotation marks etc.

Is there some setting I have to click on, to ensure I get a display that will give me these various icons or must I just wait till I get lucky!?

Thanks for any enlightenment, folks.

All at Sea