If labels have been moved then they can be automatically returned to their default position.
To re-set a label's default position on the map:
•Highlight the layer in the layer list and click the Move labels by dragging button 
•Right mouse click over the label and select Send label home OR right mouse click over the object and select Bring label home
This can be done for multiple selected objects or an entire layer at a time.
•Highlight the layer in the layer list and click the Move labels by dragging button
•Hold down the CTRL key and left click with the mouse to multi select objects on the layer OR Ctrl + A to select all objects on a layer
•Right mouse click over the top of a now highlighted object and select Bring Selected Labels Home
