You must have the application permission Manage Marks to edit tags that are available for use in all cases. However, you require the permission Manage Marks/Tags in a case to edit a tag that is available for use in that case only.
To edit a tag
Do one of the following:
If Discovery Accelerator lists a lot of cases, you can filter the list with the fields at the top of the pane. As well as filtering the cases by name, you can choose whether to list any research folders that are associated with them.