Unclaimed adds an "Unclaimed only" checkbox to the loot tab of the Adventure Guide (Encounter Journal). Tick it and the loot list hides everything you have already collected, so you can see at a glance what a dungeon or raid boss still has for you.
With the box ticked, the list shows only uncollected transmog appearances, mounts, pets, toys and other learnable items such as druid forms. Items with no appearance to collect, such as rings, necklaces and trinkets, are hidden, along with reagents, gems and quest items.
An appearance counts as collected if you know it from any source, not only from that exact item.
There is nothing to configure. Untick the box to see the full loot list again; your choice is remembered between sessions.

