You can fix the graph and layout position of a department. This prevents a department from being part of an adjacency graph or block layout improvement exchange. However, a department may still move in the block layout because other departments move around it in a sequence of exchange improvements. There is currently no foolproof method or status switch that keeps a department exactly in its original location in a block layout.
For example, follow these steps in order to fix the shipping department in the back of the layout and the office department in the front of the layout. First, move the node corresponding to the shipping department to the highest row in the adjacency graph and the node corresponding to the office department to the lowest row in the adjacency graph. Then, set the status of both departments to be fixed in place. Finally, set the layout construction procedure to use the level building orientation and not to attempt any improvement exchanges. The shipping department will be at the back of the block layout and the office will be at the front. If you allow exchange improvements, the shipping and office departments may still be at the back and front, respectively, but this is not assured.