I would like to explain why I chose it, to the next person who is asking the same question?
Along side with providing users with answers to their questions, Stack is designed to provide a future reference for many users. In order to achieve this, you have to retain a decent structured Q&A, so the question, comments and answer(s) have to be precise in their usage, so are all easily understood and clear throughout.
This ensures other people wanting an answer on the same question can read through the thread in its entirety and quite easily understand due to a decent structure, and so obtain a potential resolve to their issue without too much fuss.
- The question should remain solely the question, when read it should
outline what is being asked and nothing else (ie no "thanks to Steve,
main man" or "All solved now");
- Question comments should be relating to finding an answer for the question. They
are often pointers to things to try, and sometimes are a snippet answer ("have you tried" etc) which can be as useful as an answer to other visitors if it hits their scenario problem;
- Answer(s) should be concise and clear replies directly answering
the question, with possibly other relevant info;
- Answer comments should be relating to that specific answer, adding a bit more info, or pointing out a potential issue, etc;
Where can you explain why you chose the answer you chose?
There is no real need as your selecting a chosen answer means "this is the answer that answered your question".
Anyone else finding your question with the same/similar issue will likely find the chosen answer also helpful, if not then the question wasn't outlining a similar problem or was badly written/worded.
If you feel the need, however, put it in the comments on the answer you chose. I don't see the need, but this would be the best place.