The only way to safely store a list format is to make use of styles.

In Word 2007, you can do this to create a list style: On the Home tab, click
Multilevel List, and then click Define New List Style. Type a name for the
style. Click the Format button, and then click Numbering; Word displays the
Modify Multilevel List dialog box where you can choose the desired bullet or
number formats for each level, and also link each level to a paragraph style
(see http://www.shaunakelly.com/word/numbering/OutlineNumbering.html for
assistance with the dialog box).

After you've created the styles, they will show up under "List Styles" at
Home tab | Multilevel List. To apply numbering to text, you can apply the
list style but if you associated each numbering level with a particular
style you will find it easier to apply the styles as appropriate.

To edit the numbering, click Home tab | Multilevel List. Under "List
Styles," right-click the list style and choose Modify from the context menu.