You can view all notifications on the panel second from the left.
You can view notifications on all conversations you’re a part of by clicking the bell icon found in the lower left corner of the panel found on the extreme left. The list has four tabs: All, Tickets, Mentions and Comments. Use them to filter what you see. Click "Mark all as read" to clear the unread count.
You can mute or unmute the notification sound by clicking the speaker icon next to the title Notifications (circled in the screenshot below). Notifications still arrive in the list when the sound is muted.
