After you have imported a Cad file you can select the drawing in the 2D view and get the following options:
Lock Position: You can't move the drawing in the drawing area. Note, you can still move components that you have placed on the drawing area.
Activate 2D: By deactivating the 2D you will not risk moving objects accidentally. However, this removes the possibility to copy, move, snap or select objects in the 2D view. To activate the 2D again, click the grey border that surrounds the drawing and select the Activate 2D option.
Elevation: Set the desired elevation of the drawing.