Our memories are actually reconstructed every time we think of them. They aren’t movie clips that are stored in the brain in a certain location like files on a hard drive. They are nerve pathways that are firing anew each time we remember the event. This makes for some interesting effects. For example, the memory can change.

https://www.blog.theteamw.com/2009/11/01/100-things-you-should-know-about-people-6-memories-are-reconstructed/