My dog insists on walking in front of me at the end of the leash unless I give her a treat. What do you suggest?

My dog insists on walking in front. Not necessarily pulling but taking every bit of leash to where it’s not really loose leash walking. We use a martingale or slip chain collar for walking. I stop and change directions when she moves ahead. Most of the time she notices that I have stopped before the leash gets tight and she stops and turns with me then She will follow until a treat is given then usually moves ahead again. She does pretty well if we are working in an area like around cones. Her focus is on point with obstacle course type walking but not on leisurely walks-seems always on high alert for leisure walks (obstacle walks are in same location as leisure so environment hasn’t changed) When people are animals are around it is difficult to get her focus back on me.