The phrase "change one tune" typically implies a need for someone to alter their perspective or attitude towards a situation. Antonyms for this phrase might include "remain steadfast", "hold firm", or "maintain one's position". These terms all suggest a refusal to alter one's thinking or course of action, even in the face of potential challenges or criticism. Other antonyms might include "stay the course", "stick to one's guns", or "be resolute". These phrases all convey a sense of determination and perseverance, indicating a belief that one's current approach is the right one and should not be abandoned without good reason.