How can I see my old notifications?

The notification center is nice, but as soon as I open it, ALL my notifications vanish. They are not persistent. I should have to click an x or something to be able to manually close them, but that's not what happens. They just all vanish with the assumptions that for the 5 seconds the window was open, I read and responded to all of them.

Now I can't find a VERY IMPORTANT notification - I'm going to have to search my calendar(s) for it. It's SO ANNOYING.

On my Android, they persist until you swipe them away. And, you can scroll through the history if you need to.

On my older Macs they persisted on the screen until you closed or snoozed them. BUT with this MacOS, as soon as you open and close the notfications, all the alert windows close as well.