Before installing a Lockking Security Lock or Bar the sliding door should be raised as high as it will go and still slide easily. This will keep someone on the outside from pushing up on the sliding door and unlatching most factory latches.
To do this you will need the right kind of screwdriver, either a Philips or slot driver. By looking in the hole at the bottom edge of the sliding door you can determine which screw driver will work.
There is a roller adjustment screw on both sides of the door. By inserting the screwdriver into the adjustment screw in the door you can raise or lower the door. Raise one side a little and then the other in order to keep the edge of the sliding door aligned with the side jamb. If it seems too hard to turn the screw you might need a friend to lift that edge of the door to take the weight off of the adjustment roller.
Try to keep the handle side of the sliding door parallel to edge as in the following illustration.