You can invent new thoughts and ideas, but they are always built from existing ones, as their building blocks. I think the answer to the question 'where/how' is memory 'stored' in the brain is: "It's not". I believe the brain is quantum mechanically connected to all prior states of itself (like all matter is), and so what we call 'memory' is actually a 'direct connection' thru spacetime to the actual event.
Needless to say it would take a book to describe this theory in detail, so maybe I'll write up all my thoughts at some point, but it explains lots of mysteries of intelligences once you accept this interconnection model. Everything from savantism, to instinct behaviors, to fungal intelligences falls into place.
Once you accept that all complex patterns in nature that 'evolve' are always still 'connected directly to' all prior copies of themselves, and able to exchange wave potentials, it makes many things that used to seem 'paranormal' or 'magical' suddenly have a more scientific explanation.