I believe that you lose short-term memory before you lose long-term memory.

I remember going to a health store in San Francisco around 1980, and the person working there said that if I took lecithin, I could improve my memory. I told him that I wanted something to help me forget, as I remembered too many things. I still remember a lot of things that I wish I could forget. I never forget anything that was embarrassing to me. My mother and her mother never forgot anything that they regretted, but I try to be more like Edith Piaf:

Wow, I was just today trying my best to remember someone from way back when I was a kid and just could not remember it. He was a slumlord and very eccentric - he used to pick up rotten fruit that he found on the side of the road and give it to us. So he was eccentric and kindhearted but he lived like a homeless person and he was actually a multi-millionaire.

I don't have a good memory, yet my fraternal twin sister does. I can ask her things from our childhood and she remembers them!

Some are fortunate to have good memories.

That said, I agree that short term memory goes first. Maybe it's because the longer something is in your brain, the better chance it will be remembered?

My mother was a big Piaf fan and she had several records played until worn out that I heard when growing up. My favorite song was (and is) Milord.

Memory is funny, it is selective, and I'm not sure that how it works is yet well understood. I don't remember "everything" and I don't think I ever did, A long term marriage and many long term friendships provide instances for me to be in discussions about past experiences and events and often things come up that I've forgotten about. What I do or don't remember doesn't seem to fit any particular pattern and I'd say the same is true for those others too.

I have memories of things that scared me when I was very young, 3 years old. Fear and remembering that fear probably keeps us safe. A learned lesson.