The direct answer is that they were down voted because someone wth sufficient reputation decided to do so; beyond that, because voting is anonymous, and voters do not need to justify their votes, we really can't say why someone decided to do so. There are currently 5085 people who are eligible to cast a down vote. For each of your posts, one of them chose to do so. If the person(s) who voted on your posts choose to weigh in here, your question has a more direct answer; otherwise, we can just speculate.
So, entering the realm of speculation, someone might not like the questions because they're not "the Mac way". The screen-top menu bar has been a core part of the design of Mac interfaces since its inception, and changing it would not be a minor hack, but rather a fundamental modification to the system. Someone might have thought your question should show more research: I tried this and this but they didn't work, so what else can you suggest. Or someone might just be having a bad day and took it out on your post. Someone might have been trying to hit the up vote button and clicked or tapped in the wrong place.
You seem to be trying to learn from the votes, which is commendable, and the lack of comments makes it much harder to do that, but the fact is, one out of 5085 people didn't like each of your questions, and it's hard to say much more than that.