What do you have if the past,present and future are constantly changing?

You have your memories.

Do you have history?

You have only your own history of memories that you can count on.

What you experienced really happened.

Did world history really happen?

Maybe.

It depends upon what time line you are presently on.

So, when the past, present and future can change at any moment this changes

history at many points.

So, can you count on world history staying the same in the past, present and future?

Not really.

You can only count on having experienced what you actually experienced and to some degree what friends and relatives experienced and that's about all.

Why is this important?

If you think that Time travel is real then this is the reality we all face at some point.

If you know this is what is real then how you see things changes a lot.