The first random value is always the same when using randomSeed

Thanks for your reply~
In fact, I use randomSeed() somewhere else to generate some pattern, and the seed is determined according to the user’s input. Later I want to simulate arbitrary input to test the program, but I found once I use randomSeed(), I can’t reset it to the “random()” state. So I change the seed in runtime. Then I found this situation. Is there any way to switch between seed mode and default mode?