How to Access More Buttons or Remote Functions?

You can access additional features and functions any time by long pressing the KEYPAD button (9 dots) on your Control Center remote. 

Once the 'More' menu is displayed, you can control your device both via the Control Center remote, as well as using the focused and selected states on the 'More' menu user interface.

You can press the KEYPAD button a second time to reassign functionality for secondary button actions. 

See article on how to use Control Center to Control Set-Top Boxes (STBs) and article on how to Customize Buttons On The Control Center Remote.