I asked a question on Stack Overflow, but after a few days it became Community Wiki. Why?
I think it is related to the number of editions of the question, but I'm not certain.
You edited your question more than 10 times, making it a community wiki.
This is a rate limiting measure; don't bump your question with minor edits to get attention so often. See Why does repeated editing by same user lead to community wiki?
If this happened to your post for legitimate reasons (your post evolved over time, following the complexities of a changing question, or because of new insights to a complex problem), flag your post for moderator attention, use
other and request that a moderator revert the CW flag change.
This has happened to me once or twice, and the flag has always been quickly handled and my request to revert honoured.