At present, each storage module has one side as input and one side as output.
Often I'd like to use the same side for input and output, so as to make my belts less spaghetti.
If you click on the storage, on the dialog that appears, there should be a tiny picture which would allow you to click on each entrance/exit and change the direction, so you could mix inputs and outputs on both sides of the storage.
This would also allow you to reverse the direction of the storage without having to "move" it.
Cheers,
Chris.