As in, what is the telltale sign that you should do this?
It is going to be very hard to give a solid answer without more information.
Many students change their major after starting university. This is very common. When students graduate high school, they are often not aware of many majors that exist. Also, regardless of what you are going to major in, at the point that you graduate high school there is a lot that you don’t know about your potential future major and not really all that much that you do know.
Some people change majors because they discover that they don’t like what they were doing. Some take a few classes in a different field and discover that they like it better. Some take classes in a general area such as “biology” and discover that they like a very specific subset of it. Some realize that a change in major will give them a better chance at a solid career after they graduate. Some discover that their intended major is just too difficult for them and they are not able to do it.
If you change your major late when in university it might, depending upon circumstances and details, take longer for you to graduate university. I personally would not worry about graduating a year later and a year older – life is not a race. However, an extra year can be expensive and you should consider the financial implications of a change in major.
If you can afford it and if you are sure that you want to make a change, then it should be fine. I would not want to be locked into the wrong career for life just because I had started with one or two years of university in the wrong field.
Also, it is not unusual for students to get a master’s degree in a field which is related to but a bit different from their undergraduate degree.
I think you should see your advisor and maybe the counselor at your school. From your previous posts it sounds like your parents would strenously object to any changes. It will probably help you to discuss your concerns with the professionals at your school.
When you’re sure that you want to change your major and you are failing courses in your current major or are otherwise no longer interested in the coursework. Take a class in the new major (preferably higher than introductory level) and ensure that it is what you want to study.
I would also agree that it is important to consider the financial implications of changing your major. If you are a sophomore, it might not be such a big deal, but if you are a junior or a senior, this might set you back a semester or two. The best way to determine this is to speak with an advisor.
Is this a rhetorical question, or is it a question that applies to you? Go see the academic advisors at your college. This is why they are there.
I have seen people say “I want to be an engineer” but then they struggle in pre-calc in college. Probably time to think about another major. Or they want to major in Chem but get a D in Org Chem. Or they want to major in English but hate writing papers.
One tell tale sign is that you are struggling in the pre-reqs to the major.
But once you start taking classes in your major, you have to see if you don’t like one aspect of the major or just everything about it. Like I didn’t like physical electronics, but was happy with digital electronics. So I just make it through Physical electronics and not take more classes in that area.