Remove the covers on each side of the stands to expose the bolts. Unscrew the screws on both sides of the covers with a Phillips-head screwdriver.
Remove the mounting bolts on the side of the stand that hold the tubes in place.
Pull the flat guard off the posts and pull the stand from the tube. Adjust the tube height by sticking the posts into the needed height position holes. Place the guard back onto the posts.
Screw the bolts back into place and repeat the process for the other side.
Screw the covers back on to the stands.