How to use random seed as intended.
The Block is intended to set the Math blocks random number generator.
See Random seed - Wikipedia for a discussion about the theory.
The Block random set seed is used to set the seed for the randomizer in the Math blocks to always startup at same place. You'll get the same sequence of "random" selections every time you restart the app using the code on my example. To get a different start yo sequence change the seed from 2023 to any other value. 
Try the example and see for yourself., you should see the identical 'random' sequence of integers 