Of late, upon hearing or reading something unfamiliar I've begun saying "If I ever knew that, I don't recall." It may be a dubious distinction but given how much I've taken in over 64 years, that statement often seems more accurate than saying "I never knew that". More significant, it's less self-deprecating than that "...senior moment..." nonsense.
I've also harmlessly fantasized how cool it would be to be able to store everything important I read, see or hear from here on in. I'm not greedy - I'll gladly re-read all the seminal books, re-watch all the documentaries, re-listen to all the worthwhile music provided it all sticks with me this second time. Even better, I'll trade in all the garbage I do remember - old phone numbers, 1958 batting order of the NY Yankees, who recorded "Expressway To Your Heart" - if the stuff I really want to remember would just stay put so I could retrieve it at will.
Didn't I read somewhere that the brain is capable of doing this?