For example, if want to change the position of a part label while the lower layer is displayed, dragging the part label will select the part placed on the upper layer and drag it, resulting in unintended part movement.
Would like to be able to select only the parts in the selected layer.
You can lock parts that you do not want to move. Checkbox in inspector for individual parts. You can also select multiple parts (drag select or other options), then use Lock Part on the parts menu.