I read a lot of articles on this and all seem to agree that the brain storage in neural connections is tremendous but that doesnt explain why we forget things so easily and have such a modest memory in our subjective lives and we use much humbler devices to store information, i specifically wanna know if we can really store this information but the problem is we cant acces them as efficiently as a computer can or the whole process of storing this information is different than a hard disk on a computer. None of the articles i have read make any comments addressing this question. Links to relevant information on memory processing and storage will be appreciated.
The brain is trained to remember patterns and predictable associations. Randomness is the absence of patterns, so it's the exact opposite of what the human brain is for. A human can remember random numbers to about 67,890, which is the world record digits of Pi. That's about 20 pages of irrational numbers. Some people can remember 20 pages of word documents.
To memorize random numbers, the brain has to join colors, places, objects, people, animals, onto the randomness and construct a story to which the randomness can correspond to. It gives an idea of what the human brain is very good at memorizing, which is real-world phenomena through experience.
The human brain actually predicts what it has seen before it knows: It represents an expected object, personality or event from imagination (for example if you see a rabbit/cat beside the road and it turns out to be a bag). New objects like a page of random letters are compared to previous patterns of sensory input.
There are regions of the brain which are especially designed for tesks which are more like computer-memory, especially the task of geographic memory used for path-finding, food sources, which is called the hippocampi, which taxi drivers have very developed.
A computer actually uses man-made tools to do the memorization. A computer can't design a hard disk or a memory module, the computer uses human memorization tools, which humans can use too if you change the rules of the game a bit... they can use pen and paper... in that sense humans and computers are equal, with the computers being subservient to the humans.
Our brains usually make associations to different words including images, sounds, emotions, etc... which help reinforce the neurological patterns required to memorize sentences, etc...
To remember something, it must also be repeatedly 're-thought' to strengthen the memory. Eventually with enough conscious and subconscious repetition of a thought, these neural networks for that memory will move to the hippocampus where long term memory is stored.
memorizing 'random letters' doesn't seem to have much of a use. Making connections to these different letters will help give them meaning that your brain can hold on to allowing you to hopefully (with enough practice) memorize the whol word document.
There are however people (some considered savants) who have an ability called hyperthymesia which forces them to be able to remember everything that they have experienced in their lives.
This article: https://www.psychologytoday.com/us/blog/defining-memories/201706/why-we-forget discusses in great detail why we forget and I strongly suggest you read it (I find it very interesting).
I'd just like to add that, in addition to what has already been said, it can be a lot harder for the brain to memorize information that it doesn't find useful or relevant. As someone with ADHD, this is a common issue for me. I find it significantly more difficult to not just pay attention to, but remember information on topics that I don't find intellectually stimulating. I believe this has in large part to do with the way my brain filters out information that it deems unnecessary to remember. After all, why waste precious mental storage space on a word document of random letters? It is still possible to commit that kind of arbitrary information to memory, though, as we've seen from people who've managed to memorize thousands of digits of pi, but that takes a lot of practice and dedication, as the human brain was never really designed for such a task.