Use the Align tool to align the scan in a neutral position before placing measurements or for moving components like a lock dummy into position before socket design. With align, you are assigning the camera angles (what is part of the scan is anterior facing, etc.)
First, try the Auto-Align feature. You can find this in the toolbox after you click Align. This will automatically align your scan in an upright position. To make further manual adjustments, click and drag on the angles and bars in the colored gizmo.
Make sure you are clicking directly on the tool. If you click and rotate the free space, you are viewing the model but not truly assigning the camera angles.
Pro Tip: Make sure that the scan is centered on the grid. If it's off center, the scan will jump around when you use the left and right camera angles.
Once finished, make sure you check the left and right camera angles to make sure you are happy with the alignment.