Are you asking where you can change the default page permissions?   Here are a couple of options (although not global, but at least an option to answer your issue):

 1. Go to the top-level parent page, and set the permissions as you would like (i.e. view for Everyone), and then your child pages will have those permissions as the default setting is for all new pages to 'Inherit Permissions from parent page.'

2. You can do the opposite, and set the parent with the most restrictive, and then uncheck the option for all child pages, and set them manually.  

 Alternatively, when you create each page, the default permissions on each new page created are Admin Edit/View, and no other permissions, Although this may appear as a design defect, it actually makes a lot of sense.  By default pages being created with this permission set, it allows admins to create a page, get it all set the way they want and make it production ready, before anyone else can see it. 

 I hope this has helped.

Make It a Great Day!

D-Man