Change Default App Role

How do I change the default app role form VIEW to NONE within Member Permissions when adding new member. Right now, the default app role of VIEW gives view permission on all apps to a new user. All our apps are for different clients and we do not want one client to see the app/config of another client. Currently, I work around it by setting the app permission to none for all the apps immediately after adding a new member but with the number of apps growing, it tends to be a tedious manual task.