Using "selection" parameter in a Scatter plot

[zbouslikhin]

Hi, This is probably due to my low skills but I think I'm missing how to use the parameter "selected" in a scatter plot. I'm trying to select certain points by giving the x,y,z indices and then, change the color of the selected glyph but it always select the same points (The very first points that were plotted) no matter what the given values are. Here's how it looks like: Am I missing something?

EDIT: I've just noticed that "selection" and "selected" are two different parameters. I'm looking for "selection" tool & how to use it as I couldn't find any detail about it in the doc (basically, I'm trying to change the color and size of chosen points without using Lasso).