You offered to go back to it and explain it better. Would you?
"I don't know much about preparing taxes, so I take my taxes to an
accountant and he tells me what I should do, that I should take such and
such deductions, and all that. So I do it."
In your example, you do make an informed decision about your taxes. You decide that rather than fuss with it yourself, you'd rather pay someone else to do it. That's still taking responsibility for it and making a decision about it. I don't understand the bit about the computer problem.
"As an individualist shouldn't I be able to make those decisions about
taxes on my own? Because I should just do it, and get it done, and not
complain that it's not my job."
You do make a decision about your taxes on your own. See above. Being an individualist doesn't mean being a solitary being and abstaining from other people. You don't have to complain at it not being your job. It is your job to see that they get done, whether you do ir or whether you find someone else to do it, whereupon, you're still getting it done - just using someone else's skills for it. That's what you're paying them for.
Ok, now I understand what you mean about the computer thing. Taking responsibility for things and individualism are two separate things, but since you're bringing up responsibility, we can talk about that. It's not his computer. Therefore, it's not his responsibility to do anything with your computer. If he agreed to fix it, then it would be. In this case, he is being responsible (and nice to you in not trying to swindle you) in refusing the job. You aren't forcing him to do it. You're asking him to. He's saying no. That's not being irresponsible. That's being honest.
"... in order to specialize one has to sacrifice other knowledge. "
I think this is a victimized view. Examples?
In your Atlas Shrugged example, it is the train conductor's responisbility to get the train moving. If he doesn't trust the information he has, it's his responsibility to put effort into finding out. And unless I remember this incorrectly, she does take action to find out what's going on, doesn't she? Doesn't she walk to the next phone? Or does that happen later in the book? Well, regardless, I lack information. You're welcome to choose a different one or I could look it up.
Yes, military structure is an inappropriate place for absolute individualism (which, I'm skeptical even exists - I think we've talked about this before, but we'll save it for some other discussion). You're expected to be an individual within a collective. Lots of people are to move as one for the most successful operation. That does not, however, mean a soldier should stop thinking.
"I don't think that a military could function if it was all individualists. Likewise I think many other organizations benefit from this same structure. It makes for fairly efficient operation, so long as everyone is competent at the job they are supposed to be performing."
Right, but that doesn't mean they shouldn't think for themselves. Else, how do they catch mistakes? Suddenly, you have the Emperor's New Clothes scenario.
"There's been a study of the most effective corporate CEOs.  One of the things that they found was that they were reasonably selfless. They did things, and made decisions, not for their own glory, but for something
greater than themselves. Another aspect is that they admit that they don't know something and they seek expert advice on the topic instead of
making rash or uninformed decisions."
What's the study? I want an operational definition of selflessness. Aside from the socratic "define this" method, I suspect the study is flawed. And yes, I'm a strong supporter of admitting to when one doesn't know something. That doesn't make one a socialist or collectivist or communist or an anti-individualist or anything of the sort. It's taking a step in the right direction. First you admit you don't know something, then you either decide you don't want to find out (for which there are a few reasons, some of which I support and some of which I think are not respectable, but we can talk about this later) or you decide to find out what it is that you don't know. Saying you know something when you don't is simply lying. You're also liable to make false assertions in the process which modifies one's view of reality which, I think, is immoral. Lying to yourself is just as bad as lying to someone else. I digress.