The default collection option enables you to select a collection, and then effortlessly add and remove assets from that particular collection.
To set a collection as the default collection:
On the MAM dashboard, click the Default Folder icon located on the top toolbar.
Select a collection from the drop down menu.
When you select a collection as a default, the text colour will change to a dull grey, as shown below.
Once you have selected your default collection, you can add assets to that collection, or remove assets from the collection.
To deselect a collection as the default collection:
Click on the collection in the menu, and it will no longer be selected.