Every KeepandShare account has a single special page called it's "Share Page"- it's the place visitors come to see if you've shared any information with them.
All share pages are always public. There is therefore no need to 'set sharing' controls on share pages.
Rest assured, by default all information in your account is always private until you share it with others. Even though visitors can see your share page, they cannot see any information inside of your account until you share it with them.
Here is how to get folders and documents to appear on your share page.
If you have shared any information publicly, it will be displayed in the bottom half of your share page to all visitors.
If you have shared any information privately (i.e., with specific KeepandShare users), then your visitors must log in to authenticate themselves, after which your share pages shows them both public information and the information that has been shared privately with them.