If you change the duration of the topmost component of a paint object group (e.g. a text object), any objects contained within will also change, as long as the duration of those objects are the same as the parent object. In other words, when you create text, if you grab the end point of the text phrase, it will extend all of the letters automatically, you don't have to go in and do them manually at all.
composite layers work differently than paint objects, however - to extend a layer's duration (a still, for example), you need to extend the footage first so that the layer "sees" additional footage, then drag the layer out point.
Another option is to go to where you want the out point to be of any item and press the period key on the keyboard to automatically extend the current object and all child objects to the current time location.
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Greg Niles
combustion Product Specialist