Enabling Timeline Tracks
To the left of each track in the Timeline layers list is an activation checkbox that turns
that track on and off. When a track is turned off (disabled), it is ignored in the Canvas.
Not only can you turn video or audio on and off, you can also disable or enable effects
such as masks, filters, and behaviors.
Disabled tracks appear dimmed.
Activation checkbox is turned off.
To turn visibility for an object on or off
Click the checkbox at the left edge of the track you want to control.
When the box is checked, visibility is on, and when the box is unchecked, visibility is off.
Additionally, when a track is disabled, the entire track is dimmed in the Timeline.