This page allows you to configure the default settings for new channels. It is identical to the page found in the Channel Properties dialog and is described in detail there.
Changes that you make here will only affect new channel subscriptions that are subsequently created. Existing channels will remain unchanged. Click on the Apply to channels button if you want to apply the settings here to any of your existing channels.
If you want to change the default presentation settings for your channels, you can do this from the Display page.