You can set base permissions that apply to all members of an organization when accessing any of the organization's repositories. Base permissions do not apply to outside collaborators.
By default, members of an organization will have Read permissions to the organization's repositories.
If someone with admin access to an organization's repository grants a member a higher level of access for the repository, the higher level of access overrides the base permission.
If you've created a custom repository role with an inherited role that is lower access than your organization's base permissions, any members assigned to that role will default to the organization's base permissions rather than the inherited role. For more information, see "Managing custom repository roles for an organization."
在 GitHub.com 的右上角，单击你的个人资料照片，然后单击“你的组织”。
In the "Access" section of the sidebar, click Member privileges.
Under "Base permissions", use the drop-down to select new base permissions.
Review the changes. To confirm, click Change default permission to PERMISSION.