To Move a List Item in Multiline Text Down a Level
If the ribbon is active, double-click a multiline text object to open the MTEXT ribbon contextual tab. If the ribbon is not active, the In-Place Text Editor is displayed.
Place the cursor at the beginning of a list item and press TAB.
The item moves down one level and begins a nested list.
Press ENTER to start the next item at the same level, or press SHIFT+TAB to move the item up a level.
To save your changes and exit the editor, use one of the following methods:
On the MTEXT ribbon contextual tab, in the Close panel, click Close Text Editor.