To change the value displayed for an entry in the list of values for an optional field follow the description in the post entitled "Changing the configuration of an item type" until the Item Types and Lists of Values are displayed.
Any of the lists of values, e.g. Item Status Type, can be updated. A new value can be added to the list or one of the existing values edited. To add a new value click on the plus sign to the left of the Title of the list of values in the header bar.
Complete the Title of the value, which will be displayed in the application if this value is selected, the order in which the value should be displayed in any drop down list, leave the In use flag as Yes, and complete the description so that other administrators understand what you intended with this value.
If you wish to update an existing value, click on the ellipsis (three dots) displayed after the Title and select Edit.
Any of the fields may then be updated.