The countdown timer counts down to the next event (Events > Events in the CMS) that has the category "Live Service" assigned

You can edit the text and where the countdown timer links by going to Content > Livestream > Live Stream Links

The first link will link to your Livestream page, and the second link is where you can add sermon notes.

The "Name" field is the text that displays when the timer is live. The "Description" field is the text that displays when the timer is counting down. The "link" field is where the timer links.