Particle System not showing entirely

[unity_kjqneH-la-1cKw]

So, I am new to Unity, and I’m trying to follow the Pong tutorial, already in the end… Right now it asks to put Particle System as child of a GameObject ( the goal of the pong game ). BUT, when I do it and try to play, particles appear but they look like limited by a invisible box, they dont show all. What can I do ? Thanks !!!
I am doing this tutorial: http://unity.grogansoft.com/beginners-guide-create-a-pong-clone-in-unity-part-10/

They should look like this :

[Guy_Yome]

You could try messing and tweaking some values. Probably the lifetime of your particles is too low. But we don’t have much detail. That’s my guess.

Try putting it at somethin like 10 to exagerate and see what happens.