Boundaries are about what you want. If something does not bother you, then it does not bother you! Boundaries are not moral objects but guides to help us think about and organize our own lives. The fact that someone else has bad boundaries should not affect us other than we decide if we like/do not like their general way of relating to us and adjust our own boundaries accordingly.

With the person asking you numerous times why you can't fix her computer. If she asks in a way you do not like, you say something along the lines of, "I do not like being talked to in that tone of voice." You let the other person know where you are; that is what boundaries are for. If you don't care about her tone of voice/personal problems and only care about the question, you answer the question or say something like, "I have told you before I cannot fix your computer because of X, Y, and Z, and I am not going to discuss it with you again." When they bring it up a 3rd time you reiterate, "I have told you before why I cannot fix it, and I'm not going to discuss that again." If you don't have any trouble with the person asking a zillion times/as many as they want or need to, then you patiently tell them the answer each time. It's up to you. You tell the other person where YOU are, not where they should be or what a pain in the tush they are or anything else about them.

You are allowed to like/dislike someone's attitude or even alleged attitude and when they are dealing with you one-on-one you tell them what you are thinking/feeling about their attitude (not about "them"). "It sounds like you are annoyed with me, I wish you would tell me about it instead of copping an attitude. . ." and they either are surprised and explain that they are not annoyed with you or meaning to sound like they are, etc. and you two hash it out and get together better or they get further annoyed or ignore you or explain they are annoyed with you because you won't fix their computer and they think you can and you explain again why you cannot and add that you are sorry if they do not understand but you will not be fixing their computer and would they please not bring it up anymore.