The Agent can’t change a screen recording’s display or background yet, but the controls are in the top bar.
Pick a display
Select the screen recording, then pick a display from the menu at the left of the top bar.
Background, bookmark bar and sound
Click ⋯ at the right of the top bar.
If you’ve re-timed part of the recording with sync points, its sound is muted automatically and Unmute is greyed out.