When should I alter a question rather than create a new one that's very similar?

Question

I wrote the following question:

How can I safely allow a php based website to create a linux user and interact with the environment?

I realize now that, based on a lack of understanding at the time, my question title is not exactly what I mean to ask.

What I mean to ask is "How can I automate the Linux account creation process after a new user signs up?" (Or, something similar.) My goal is to have an answer that explains how to do this, whether PHP is the correct approach or not.

There is some interest in the question. If I change the title, it alters it pretty substantially.

If the answer to that exact question is "You can't" (for sake of argument), well, technically that is an acceptable answer but I get no closer to solving my problem or having an answer for what I'm trying to accomplish, so would I accept it and write a new question that going to be extremely similar? Or should I alter the title of this one?

Answer 1

In general, I would say, when your question has been answered and upvoted, especially if the answers have upvotes, please don't change it unless you strongly feel your question has been misunderstood. Ask a new question instead, linking to the original question if it provides context.

In this case, I feel your uncertainty, but if you explain in the new question how the new one is different from the old one (convincingly!), your new question should not get closed as a duplicate of the first.

My reasoning: of course we want to help the person who asks the question, but we also want to create a library of questions to help future users, so, hopefully, the old question will be useful to someone else, even if it was not very useful to you.

Answer 2

I would go so far as to say about the only time you should alter a question other than to add further information requested in comments is when it's been closed. Just because you've asked a valid question that wasn't the question you meant to ask doesn't mean that it has no value. Our objective is to help as many people as possible as efficiently as possible. The answers to the question that you asked (even in error) may be of value to others who have the same question. If a question has been closed as unclear you should edit it to add clarity. If a question has been closed as a duplicate and the answers to the called duplicate question don't resolve your issue you should edit your question to make it clear what you tried and why your question is not a duplicate of the called duplicate. (Simply saying "Not a duplicate, tried everything" isn't sufficient.)