This is because what you're throwing in your Composition is not an effect, but an animation preset.
Animation presets are pre-made blocks of animated content you can use in your project. It's important to note that unlike the "canned" presets in some applications, animation presets make use of the standard feautures in After Effects. In fact, you can save your own animation presets. A lot of users do this, so they don't have to re-create something every time they need it.
But, of course, we're talking here about the animation presets that are installed with the application.
So, as it happens wth animated content in general, these animation presets have a starting point and an ending point.
If you twirl open the layer in the timeline, you'll see there are a few keyframes that are animating the effects and properties used in that specific preset.
You could select the ending keyframes in the range and move them to a later point in the timeline. That will also make the animation slower (which is what happens when you move keyframes away from each other in time). It may or may not be a problem depending on what you want (and how long is the time span along which you're moving these keyframes)
Which preset in the "Backgrounds" category are you trying to use?
Thanks, Adolfo - finally makes sense. I'm still new to AE and barely
scratching the surface. Hope I don't get everyone's back up on the forum
with some more inane questions
> I'm still new to AE and barely scratching the surface. Hope I don't get everyone's back up on the forum with some more inane questions
If you keep asking questions that provide plenty of information for us to figure out how to help, no one's back will go up. That's what we're here for.
If you're just starting out, I recommend working your way through the materials listed under the "Getting started" section on the After Effects Help & Support page.
For information about effects and animation presets specifically, check out "Effects and animation presets overview".