There are two ways to re-order boards or circuits.
Using the Ribbon
The first is to select the board or circuit and then use the move up/down items in the ribbon for either the board:
Or the circuit:
Using drag and drop
Starting with version 2012.2.761, you can now use drag and drop to reorder boards or circuits. To do this, select the board or circuit you want to move by clicking and holding the left mouse button on the indicator area at the left of the list of boards or circuits. Then drag it to where you want it to go and then drop it (by release the left mouse button).
To move an item to the start of the list, drop the item on the start list headers. To move an item to the end of the list, drop it just below the last item.
You can do this in the Board Manager, the Board Selector and the Circuit and Test Grid as shown below.
Three phase boards
When you reorder circuits in a three phase board, they move as a group of three.
Tip: if you need to reorder the circuits inside a group, change the board to single phase, reorder the circuits, then change back to three phase.