Visitor Access defaults allow you to set the default access setting for new sites created in the account. When you create a new blank site, it will inherit the default Visitor Access, as described below, which will not affect any existing sites. To change the Visitor Access of an existing site, you can access the Site Details menu of the site as discussed in this article.
To change the settings:
Click on Account at the bottom left corner, then select Account from the menu.
Under Account Settings, select the Visitor Access tab.
Select the preferred Visitor Access default for new blank sites.
For more information regarding the types of Visitor Access, you can check our article, Visitor Access: Public & Private Sites.