How to change the default security group for a new item?

By default, all sites, lists, and libraries in a site collection inherit permissions settings from whatever is directly above them in the site hierarchy. This means a site inherits permissions from the root site of the site collection, and a sub site inherits permissions from its parent site. A list inherits permissions from the site that contains the list. A list item inherits permissions from the list to which it belongs. If the default configuration is not changed, permissions are inherited throughout the whole site collection.

To break inheritance for the list and restrict access to it, follow these steps:

• Navigate to the site that contains the list and open it.
• Choose the List tab to open the list ribbon.
• Click Settings, and then choose List Settings.
• On the Settings page, under Permissions and Management, click Permissions for this list to open the permissions page for the list. The permission page displays a status bar across the top that indicates the list inherits permissions from its parent site, and then gives the name of the parent.
• To break permissions inheritance from the parent, click Stop Inheriting Permissions. This disconnects the list from the parent site.

Here are some important things to note:

• When you break inheritance for a list, the list still has the same permission settings that it did before. To make the list permissions unique, you have to assign new permissions explicitly.
• If you change the permissions of the list, all items in the list inherit the changes (unless an item has unique permissions.
• After you stop inheriting permissions, the status bar for the list changes. The message now states, “This list has unique permissions”.
• In addition, the ribbon buttons change to include “Delete unique permissions”, “Grant permissions”, “Edit User Permissions”, and “Remove User Permissions”.
• You can reverse this setting, and resume inheriting permissions from a parent at any time.