Create a Hidden document to keep it private. Later, you can change the visibility to include other people if you need to.
You can create documents that are visible only to you. To do this, click 
> Document (or Uploaded Document. When you finish, click Hidden in the visibility
options before you publish or save as a draft to ensure no one else can see it. To see
your Hidden document later, go to in the main navigation menu and then filter by Documents. From
there, you can edit your document and keep it hidden, or you could make it visible to
other users by changing the visibility options before you publish the document.
To understand which content types can be hidden, limited to specific people, or public, see Content Visibility Options
You can also keep bookmarks private if you don't want others to see them. In addition, if you assign yourself a personal task, no one else can see the task.