In iOS 16, why do notifications disappear?

Sorry if this is a repeat, this is a long thread, I haven’t read it, and I have things to do, I got eggs to lay, ground to scratch before leaving on a trip. But my ‘gripe’ in this notifications subject is when I pull up notifications and start reading them, some I might think about for a short while, do I want to go there and read more or not? Then all the notifications collapse back down. There is not a setting as to how long the notifications are shown, or is there one? I asked at my local Apple Store and they said there isn’t one.