Ligatures (Fonts)

Is there any possibility to remove the fonts ligatures?

I try selecting typography/ligatures from the Show Font menu.

After selecting the text I'm able to remove them, but when I deselect the text area the ligatures comes back again.

Example:
Please write "Il Mastino dei Baskerville" using the Zapfino font.
Both the "st" and "ll" comes with legatures.

Any help?