What scope does Randomize function have?

I recentlly began to use Randomize function to reset randoms and I can't understand exactlly what it does because ot appears to afect all of the threads I'm running at a time instead of I'm using new random() at it appears it only affects one thread.

My point is that I can't understand the scope of Randomize sentence.It seems it has a system scope but I can't understand the reason because the msdn documentation tells me this about randomize: Randomize uses Number to initialize the Rnd function's random-number generator, giving it a new seed value