To Reorder Toolboxes

In the Customize dialog ( File > Settings > Configuration > Customize ) , click the Tools tab.
Expand the User Tools section and expand the open DGN file.
Select the toolbox whose relative position you want to change.
Do one of the following:

To move up the toolbox one position, click the Move Up icon.

or
Right-click the toolbox and select Move Up from the pop-up menu.
Do one of the following:

To move down the toolbox one position, click the Move Down icon.

or
Right-click the toolbox and select Move Down from the pop-up menu.

Note: If the toolbox is the first item in the open DGN file or in the toolbox it cannot move up. If the toolbox is the last item in the open DGN file or in the toolbox it cannot move down.