I want to make all particles die off screen. What is the easiest way to accomplish this? I made a project where circles emit toward the camera. Once the circles clear the text is revealed. But not all of the circles make it off the edge of the screen before they die. I am still new to motion so forgive my ignorance.
Go to Inspector>Emitter>Cell Controls>Life and just crank up the particle Life values. One quick tip, you can adjust the sliders but to get higher values than they are showing just double click the numerical value and enter higher numbers. (Also keep in mind that both the Life Randomness and Opacity Over Life parameters can effect the life of particles as well.)
Definitely check out the "Working with Particles" chapter in the manual (although with even the combined Motion 3 manual and the Supplemental Documentation topping in at a whopping 1402 pages, they still don't cover every aspect of this program).