Update Issue Comment Visibility
1. Select "Update Comment Author" from More actions
User must have Edit All Comments or Edit Own Comments project permissions for selected issue's project to access/see Update Comment Visibility action at More action list.
2. Select Comments to update visibility
If user has Edit All Comments project permissions for selected issue, s/he can select all comments.
If user has only Edit Own Comments project permissions for selected issue, s/he can only select own comments.