"Time is transient. I sincerely cannot understand that time flies. And where to? Is 'time passes' better than 'time flies' perhaps? And past what? The children grow up and become considerate, and I have thoughts of time passing, but I can't grasp it."

Time itself solves many problems, each of which you saw as the biggest in the world.
And time heals.

Then you ask again:

"Perhaps I have invented time to understand all that I cannot yet grasp?"

And you ask me:

"With which index do I search back in time, which key opens a certain memory track, which light, which point of view and which motif colours the memory? And: how and why do I remember?"

Once all this is answered, you can know where you want to go. Then there is a story to tell. The moment the story is told, it is born, is about something and exists as itself.

Your last question for today is:

"Is the story really only defined when it is told? If I don't tell it, does it exist anyhow?"

There will always be a reason for recalling a story. The reason may be something that is on your mind today, or the reason may be something that everyone agrees took place. And bear in mind, that you and the story are not the same. The story is something that you have experienced in realtime. The story, that you recall, YOU have chosen. All others you have dropped, which ones you cannot know. 
Other people might.

You can consider whether the story being told is then forgotten and time is suspended.