There is only one spot to change homing direction
// Sets direction of endstops when homing; 1=MAX, -1=MIN
#define X_HOME_DIR -1
#define Y_HOME_DIR -1
#define Z_HOME_DIR 1
Check also M119 to see where your endstop is. If you have min endstop use -1 otherwise 1. If it moves in wrong direction invert motor direction, not homing direction.