Use this function to alter the default permission for new wikis.
Click "Add user or user group" to add items to the list. Search for the desired item and click "Add". Click "Ok" when all users and groups are selected.
Decide which default access rights should apply for which user or group by checking/unchecking the check boxes below the appropriate access right. To remove a user or group simply remove all checks for that particular row. When done, click "Save".
Read more about permissions.