These are the steps to follow using the web interface:
1. Click "Customize" under the "DVD" Activity
2. Click "Run the Setup Wizard Again"
3. Click the "Next" button, accepting the default selections, until you reach "Review the Settings for this activity. Are they correct?"
4. Select "Yes, but I want to add more control of options and devices for this Activity." and then click "Next".
5. Click the "Next" button, accepting the default selections, until you reach "Please review the actions for your DVD Activity".
6. You will now see "Add action for" options for when you enter this activity and for when you leave. Simply add an action on entry to set your TV to Cinema and then add an action on exit to set it back.