I think there should be a simple option in the Social Monitoring "Inbox" to mark all as read. I manage multiple high-profile accounts and seeing it always 100+ because of items from years ago I cannot scroll back to and are technically unread is bothersome. The "expand all/collapse all" options don't solve it.
Replying for Daria - I'm glad to say this is live! If you opt-in to the new Social Monitoring experience it will be in the top right hand corner (see attached image).
