Same question as before,
"I'm a total beginner and I need to make a ball roll around on a flat surface and have it leave a trail/tracks of where it has traveled without it disappearing over time. Is there a function or method that I can use to create this effect?"
I've fiddled around with the line renderer and trail renderer and can't seem to get the result I'm looking for. I'm such a novice so feel free to patronize.
I might go for something that has to do with code as Dendro suggested.
you could try looking in the scripting reference and look for "particles" in the searchbar, and look for trail renderer, and im sure there's a bit of code to change it from dissapearing over time to staying rendered.
Without disappearing over time? Try Line Renderer, and manually set its points as the ball travels, or it may be possible to set a trail renderer's time to "Mathf.Infinity" (might need to be done in a Start function, not sure if that's a valid entry in the Inspector).
Take a look at the car tutorial
They have some nice information on how to do skidmarks, and remove them...