When we create a project that contain more than one panorama, then we normally will relate those panos into a single model using references. Then there can be some miss location issues due to some facts such as :
Some times there are bad areas where stitching software can fail leading to deformed areas
Again in the stitching or also in the capturing process, there can be some issues that generates a miss aligned panorama, with no straight vertical lines, and therefore a kind of deformation
While creating the references user can introduce small deviations that generates an error on the location of the panorama
As you may already know, when you have a model the geometry is shared along all panos of the model, so you do not need to be modelling everything from everywhere. And here is where fine tune gets into the game. The app will suggest a location for the geometry, based on the information from the references, and due to the facts explained above, there can be a bad location of the geometry. So you can just move the vertical lines from the ground point and adjust it so it fits perfectly to the specific pano.
Here an important concept. When you create a vertical line from a pano, that pano becomes the root of the line. And when moved that line in the root pano, it moves in all the other panos, and also is the one used for the model information, so it's the value that gets represented in the model view.
Once you go to another pano from the same model, and drag the line, then it becames independent, because the software expects that you have moved to a correct location to make the geometry fits correctly. Then that line in that pano will not be moved anymore from the root line even it's the same line