Managing dashboard and dashboard folder permissions
To manage the permissions of dashboards and dashboard folders, you must have Administer permission on the application.
Users' access to dashboards is controlled through membership of roles. By default, role permissions are inherited by the folders below it, and by the dashboards, reports, and folders that they contain. So, if a role has Edit Dashboards permission on the application then all users within that role can edit every dashboard. You can manually add or remove permissions on a particular folder, dashboard, or report. In doing so, you break the inheritance from the application. Typically, you edit permissions on folders, not on individual dashboards or reports.