To Change the Display of Levels Graphically

Select or fence an element(s) residing on the level(s) for which you want to change the display setting.
In the Level Display dialog, select the Change Level tool.
Do one of the following:

In the Change Level settings window, select Display Off from the Level option menu to turn off the level(s) of the identified element.

or
Select Display Only from the Level option menu to display only the level(s) of the identified element.

or
Select Lock from the Level option menu to lock the level(s) of the identified element.

or
Select Unlock from the Level option menu to unlock the level(s) of the identified element.