Enable Edit Mode first (see Edit Mode).

The Display Name can be edited in both the Class Display Names and Symbol Name (see Class vs. Symbol Name).

To edit the text you use Properties from the symbols context menu.

You see the display name which comes from the project setup.

Just override it with your text and click OK.

Now the new Display Name is shown.

The Custom Display Name is used in both the Symbol Name and Class Display Name view (see Class vs. Symbol Name).

If you want to reset the text you can click on the red cross.

Or you click on the Reset button. Be aware, that this will also reset the Images you may have selected (see Change Image ).

Now the Display Name is back to normal.

At the end of the process disable the Edit Mode again (see Edit Mode).
 

Enable Edit Mode first (see Edit Mode).

When changing the Display Name of a Hyperlink the dialog looks a bit different than before. But in regards of the Display Name everything is the same.

At the end of the process disable the Edit Mode again (see Edit Mode).
 

Enable Edit Mode first (see Edit Mode).

When changing the Display Name of an AutoCAD/AutoLISP Custom Object the dialog again looks a bit different than before. But in regards of the Display Name everything is the same.

At the end of the process disable the Edit Mode again (see Edit Mode).