How do I change a sprite's image of only one that's displayed?

Hi there, i'm working on a Plinko game with images, but I came on an issue.

I have a script that makes a Sprite with as reference the default image I added to the game, and after that it changes the image to an URL from the web. I want this change to only be made on one of the sprite's displayed in the game right now, how can I do this?

This is how my game looks:

My script: