There is a fascinating dialect quirk which has caused occasional confusions, which I think ought to get talked about. Many people who learned English in India tend to use the word “doubt” where most other English speakers would use “question”. I have been told that this is because, in one of the common languages around there, there’s a single word which is the best translation for both “doubt” and “question”, and people get told to translate it to “doubt”.
This occasionally causes confusion, because doubts and questions are not the same thing in English. For one thing, a question is a request that someone else provide information. A doubt is merely an uncertainty. For another, “doubt” has the connotation that you have been given information already, but think it may be incorrect.
What this means is that if you haven’t already got at least some information, it is at the very least highly unidiomatic to say you have a “doubt” about a topic. And if you have got some, there’s a worse landmine: The connotations of “doubt” allow it to be used as a way to not quite explicitly accuse someone of lying. If someone tells you something, and you say you have a doubt about it, you are asserting that you do not find what they told you believable for some reason. This requires that they are mistaken or lying, and a lot of the time, being mistaken about an issue would imply lying about one’s expertise or competence. Especially with technical issues.
If you have an awareness that you do not fully understand something, call it “uncertainty”. If you have a desire for other people to tell you about something, or tell you more about it, call that “a question”. Only call it “a doubt” (or doubts, plural) if you have information but suspect that it isn’t true.
A lot of people will know what you mean anyway, especially if you have other similar signs of English as a second language and they’ve encountered the idiom before, but even then, using the same word for all of these different things reduces the clarity of your communication. Every time you make people guess at your meaning, you create doubts…