The phrase "do about-face" can be used to describe a sudden change in direction or opinion. If you're looking for synonyms to use in place of "do about-face," you might consider using "switch gears," "make a U-turn," or "reverse course." These phrases can all convey the idea of a sudden and significant change. Other alternatives might include "take a different tack," "shift focus," or "change tack." Whatever phrase you choose, make sure it accurately conveys the intended meaning and fits with the overall tone and style of your writing or speech.