> That's because е is usually used to represent the same sound if it's not in the beginning of the word.
This is far from being a general rule. Your example is an exception. Consider "мера", "монета", "обмен" and so on. You cannot change "e" to "э" in these cases.
You cannot change "e" to "э" in these cases and you should not. What I mean is using "э" where you can, phonetically. Using "е" in those cases actually is "changing" although has made it into the standard.
That's not what you said in the original post. Also I would appreciate if you stop downvoting my posts, as I believe input from a native speaker may be valuable to someone.
I obviously failed to communicate that properly yet that's exactly what I meant.
> Also I would appreciate if you stop downvoting my posts
That's not me. For a spectrum of reasons I believe it's great if whoever having a relevant idea/opinion shares it, even if it's wrong, let alone different from mine. So I don't downvote anybody ever (but in some extremely rare exceptions perhaps).
This is far from being a general rule. Your example is an exception. Consider "мера", "монета", "обмен" and so on. You cannot change "e" to "э" in these cases.