The antonyms for the phrase "changing course" include staying put, remaining steadfast, and maintaining one's path or trajectory. The opposite of change, in this case, would imply a sense of consistency and direction. It can also mean avoiding any deviation or detour from the current route, whether it be a physical or metaphorical journey. Some synonyms that can describe this idea include staying the course, keeping one's eyes on the prize, and sticking to one's guns. Regardless of the wording, the message conveyed by these antonyms is one of determination and unwavering focus towards a set goal or destination.