At the end of Back to the Future, Marty wakes up
and meets his new, successful parents and family.
He of course, doesn't remember them or their history together, since it's a result of his time traveling. Earlier in the film we see that changes to the timeline take time to propagate into the future.
Did this occur to Marty's memory? At some point did the changes in the timeline impact Marty's memory, so he remembers the changed timeline?