To navigate to Threads Options, go to ACP → Setup → Options → [TH] Featured Threads and Content: Resources.
Apply prefix to featured resources - If selected a prefix will automatically be applied to featured resources. If the prefix is not available in the node containing the post it will not be applied. Additionally, the prefix will not be applied if the resource already has a prefix unless the option below is enabled.
Override existing prefix - If selected, the prefix above will override an existing prefix on resource when featured.