Walter, I have a computer program that lets me, from my home, connect to your computer and use it at the same time that you're using it. It's as if I was right there in person, is an excellent training tool and could be a good way of showing me the issues that you're dealing with. I'm not pressuring you- just throwing out the idea.
As I read through your last post another idea occurred to me. What about asking the people you work for if they can delegate the accounting responsibilities to someone else? Your bosses know what you bring to the table in terms of baking knowledge and special needs teaching expertise, right? How much are they aware of your abilities? Do they understand how irreplaceable you are? If they fully comprehend everything that you're contributing to the organization, then they should be able to live with the idea that you might not ever become computer savvy and to work around those shortcomings. They have to know that you'd make at least 10 times the money you're making doing the same thing in the private sector, right? You're obviously not doing this for the money. You're doing this because teaching special needs children is so gratifying. With everything you bring to the table and with the financial sacrifices you're making to do this kind of work, you shouldn't have to suffer through the misery of this accounting garbage- and your bosses should be fully aware of this.
Schools, as you're acutely aware, can be incredibly bureaucratic, and the last thing they probably want to do is to give you special dispensation, but, if they know what's best for them and for the kids, then I'd hope that they'd step up should you decide to ask for it. They're not going to want to hire someone to do the accounting, but I don't think turning over your accounting responsibilities to the treasurer would be the end of the world. You get your receipts and you mail them in. Done.
There's nothing at all dishonorable in saying "hey, I'm really great at this and that (one of the best), but I'm not so good at this other thing- and might not ever be good at that other thing, so if you want me for what I'm best at, you have to work around what I'm not good at- and accept that fact and give those responsibilities to others."