After switching form one craft to another, the rotators become inverted and do not function as before. (the grid fins in the picture should be extending away form the rocket body but instead they are going into the body after switching back to this craft)
Fly rocket and separate into 3 parts (core + 2 boosters)
switch to one of the boosters
Activate grid fins
switch to another booster, activate fins
switch to original booster, rotators are now inverted
4.