There is a logic to the subview behavior. The subview folder icon, when collapsed, will be located in the geometric center of the colored area taken up by the nodes in the subview, when its expanded.
The left, right, top, bottom most nodes define the edges of the subview area. You can only set the area of the subview by manually placing the nodes to force the edges to where you want them.
If the nodes in the subview haved been moved, and that changes boundaries of the area of the subview, then the subview icon will move when the the subivew is collapsed.
If the subview nodes are not moved (or the boundaries of the area don't change), then the subview folder icon stays in the same spot when the subview is collpased.
So if you want to control the location of the subview folder icon, manually place the nodes in the subivew so the area is centered on that spot.
There is a lock function, but that only keeps the operator from moving the icons at the top level - moving the subivew icons will still change the area and the location of the folder icon.