Please note, ligatures can either be Standard or Discretionary. Standard Ligatures are applied by default, Discretionary Ligatures are available through the process below. You can also 'turn off' a Standard Ligature the same way.
- You can see all Glyphs and Ligatures in the Glyphs panel as per instructions in 'Show glyphs in Illustrator'.
- Open the OpenType panel through Window > OpenType.
- On text that has the font applied, highlight the ligature, e.g. 'th'.
- In the OpenType panel with your character(s) highlighted, you can switch between the Standard Ligature and Discretionary Ligatures with the 'fi' and 'st' icons (if available)