The history of a Presentations document can be accessed in the form of revisions listed in the history panel.
Using the History Tab
You can view all revisions, which are created each time a document is shared, under the History tab.
Note that creating a presentation will automatically create a first revision. This allows you to create a blackline (covered below) from your original document. After this, new revisions are created with each share.
In the History panel you'll be able to see any remarks entered and the places where the document Milestones have been marked, indicated by a yellow star. You can use the filter drop-down menu to filter by user, location of changes in the document, milestones, or time period.
Options in the Actions Menu
When you hover over a listing for a particular revision, the entry is highlighted and you can click on the Actions drop-down menu. This will give you options for Open, Preview Revision, Mark as Milestone, Add Remark, Create Blackline, and Create Review.