When you have a technical control already set, you might want to edit it. This is possible in the technical controls tab where is visible a list with the existing technical controls.
Click on the pencil icon on the right to edit an existing technical control. For example, edit the "BBC - Vidéo - High Definition". The paremeters form ready to edit will appear on your screen.
After modifying the necessary information click on save button at the bottom of the page.