To Rename a Main Task

In the Customize dialog ( File > Settings > Configuration > Customize ) on the Tools tab, expand the Main Tasks tab.
Expand the User Tasks section and expand the open DGN library.
Select the Main task that you want to rename.
Do one of the following:

Click the Main task a second time.

or
Right-click the task and select Rename from the pop-up menu.

A rectangle appears around the Main task's name.
Type a new name for the Main task.