When working with multiple shape layers, things can get complicated very quickly, and it can be tough to select and work with the right vector shape.
To avoid accidentally selecting the wrong shape with the Path Selection tool or the Direct Selection tool (A), press the Q key.
Doing so will lock all shapes from the currently selected shape, allowing you to click anywhere on the canvas without selecting another shape. Remember to press the Q key again where you are done to unlock all the other shapes.