Unlike moving, resizing only works on one shape at the time i.e. it does not influence the other shapes of the selection. If you want to resize multiple shapes in one command then you could use the Same Size command in the Edit menu. The Same Size command makes the size of all selected node shapes the same size as the first selected shape (the shape with the black handles). The first selected shape should be a node shape of course. The edges in the rest of the selection are ignored by this command.
Tip: when node shapes have been moved or resized then their adjacent edges are redrawn and all their handles and labels are placed back to their default positions. This is sometimes undesirable . To avoid that your effort gets lost, postpone moving edge labels and handles to their final positions until when you think that the connected nodes are OK. Draw the graph first and then you can bother about the layout.