To Add Tool Properties

In the Customize dialog ( File > Settings > Configuration > Customize ) , click the Tools tab.
Expand the User Tools section and expand the open DGN file.
Expand the toolbox containing the tool to which you want to add properties.
Do one of the following:

Right-click the tool to which you want to add properties and select Add from the pop-up menu.

or
Right-click below the tool's existing properties and select Add from the pop-up menu.

A cascading submenu of property categories and properties appears.
Select a property.
The selected property appears in the Properties pane under its tab.
(Optional) To add other properties from the same category, in the Properties pane right-click its tab and select Add <property>.
The selected property appears in the Properties pane under its tab.
Do one of the following:

For each added property, click the arrow to the right of its name and select a value for the property.

or
Select the existing value and type a new value.