Also - There is no library icon! Thanks!

You _may_ be experiencing expected behavior. Kindly tolerate my presumption that you could be making a very basic mistake about how the Zotero interface works.

At the top of the left hand column there is an icon and title for "my library" if you have collections they will appear below that with folder-like icons. When you click "new collection" you get the option to name the collection. === A new collection is empty.===

Collections are akin to iTunes playlists. You add items to the collection either by 1) opening "my library" and dragging the item from the center column to the collection icon/name in the left column; or 2) by importing an item into Zotero from the web ( a database, a publisher, etc.) into an open collection. Items can be in more than one collection. All items in any collection will be listed in your library. Items can be removed from collections without deleting them to your trash. Items remain in your library. The collections exist as an organizational tool. Items in more than one collection are not duplicates unless you imported the item two or more times.

Zotero works well for many thousands of Mac users. You will need to provide more information. I am sure one of the volunteer experts here can help you to resolve your problem. Your experience suggests that there may be something unusual about your setup. A screen shot may go a long way to getting help.

It isn't clear what you mean by "my documents disappear " do you refer to the listings of items in the center column? Do you mean your attached pdf documents? What is obvious to you isn't to folks who cannot see your screen.

https://www.zotero.org/support/reporting_problems

https://www.zotero.org/support/getting_help