To see the sticky notes for the entire book or to see previous chats, you must first be logged in as the Admin for your book since only the Admin may see all sticky notes and chats. If you do not see Admin in the top-level toolbar, shown in the screenshot below, then you are not logged in as the Admin.
Once you are logged in as the Admin, click on Admin in the top-level toolbar, shown in the above screenshot. From there, click on the Manage Messages tab in the second-level toolbar.
By design, the Chats will display first. Please note that the View Chats area will display all chats that have taken place between users in your book, not just chats that you are a part of. To see the sticky notes, click on the blue area that says Sticky Note Management (below all the chats in View Chats). (You may need to scroll down the page to find the Sticky Note Management area if you have a lot of chats that continue off the page.