I generally find written explanations to be easier to undertand than spoken explanations, as I can read them phrase by phrase, pause to assimilate a phrase, and then read the next phrase. If people are explaining technical subjects by speaking to me, I have to ask them to pause while I assimilate one phrase, perhaps ask them to repeat the phrase several times, then ask them to pause again after each repetition, while I try to assimilate the phrase -- then finally go on to the next phrase, and repeat the process. Often people are unwilling to do that, don't have the patience to do that.
Don't let the fact that I write well and speak well lead you to assume that I understand things easily. It is just the opposite. I write well because I have to go over things many times before I finally understand them, and then I have to translate what I've finally understood, into my own words. Then I refer to my own text, instead of the original text that I learned the subject from. Then I go over my own text over and I revise it, and go over it again, and revise it again, and go over it again, until it gets clearer and clearer. So I get a lot of practice writing, and putting things into words, in lots of different ways.
I have gotten a lot of practice writing and explaining things, and gotten good at it -- precisely because I have so much trouble understanding things.
I can't take the bus anywhere without spending most of a day or 2 reading schedules, and then translating them into a written step by step description, of what I have to do to get from place A to place B. My story of how to get from eastern long island to a doctor's office in manhattan, is a page and 1/2 long. I put it in my pocket before I leave my home. It tells me what time to leave my home, which of the bus stops near my home I have to walk to, how long it takes to walk there, what time the bus will arrive at that bus stop to pick me up, where I have to get off and what time the bus will arrive there, directions for where i have to walk to catch the next bus, how long it will take to walk there, how long i will have to wait at the second bus stop until the second bus comes, what time the bus comes, where I have to get off, directions for walking from the bus station to the long island railroad station, what time the train comes, where I have to get off the train, where i have to walk to from the train station to get to which subway station, which subway line to take once I get to the station, and in which direction, what stop to get off, which subway line i have to fine next, and in which direction, and where i have to get off the subway train. Then i have directions for how to walk from the subway station to the building that the doctor's office is in. I have direction for where to go in the building, where to find the elevator, which floor to take the elevator to, and which way to walk once I get out of the elevator.
I keep the 2 sheets of paper in front of me throughout the whole trip, and follow the directions phrase by phrase.
The step by step direction sheets takes me 2 days to write and rewrite. I refer to on-line train schedules and maps, on-line bus schedules and maps, and subway maps, in the process of writing and revising my directions sheet. If I go to the same doctor's office a month later, I have to go over the whole process again. I can't remember how I got there last time, since it was more than a day or 2 ago. Also, everything has to be revised since my appointment is likely to be at a different time, and since bus and train schedules change. So every time I have to go to my docto'rs office in manhatten, which takes about 4 hours (would take 2 hours by car), I have to spend 2 days before hand, just revising my directions sheet. I have similar information, which i include in the directions sheet, for how to get from the doctor's office to my home.
In regard to very technical things like computer applications, say for example a word processing program or a spread sheet, I can't understand it from the documentation. I have to have both the documentation and the program right in front of me, then read the doc phrase by phrase, then do what the doc says to do, with the keyboard or mouse, and see if what it says is supposed to come up on the screen, indeed comes up. I suspect I may not be able to figure out how paypal works until after I sign up for it, and can actually see how it works, step by step.