Changes to fields for object types already used by existing package lines can have a significant impact. For example, if the column where a field value gets stored is changed, all existing package lines for this object type will now have incorrect data. Also, remember that tokens can be used in object type commands and notifications. Any changes to these could disrupt the system.
Changing information like the field prompt or description should not affect the behavior of existing package lines.
To edit an existing field:
From the Workbench shortcut bar, select Deployment Mgmt > Object Types.
The Object Type Workbench opens.
Open an object type.
The Object Type window opens.
From the Fields tab, select a field, and then click Edit.
The Field window opens.
Modify the field as required, and then click OK.