Wait, which block are you trying to use?
This one?
Or this one?
If it's the first one, you can't insert any operators into it. That block only lets you choose a color from the screen with the eyedropper.
If it's the second one, then that's odd. However, there are 255 possible colors, so if you're only using "pick random 1 to 10" the changes will be barely noticeable. You'll want to change it to "pick random 1 to 255" instead.
Does that help?
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