I am interested in software to stitch JPEGs into a movie and found the year old question and answer Recommendations for time-lapse photography software. I would like to essentially "Reopen" this question, giving a little more detail than the original question, and report on the several programs I tried that did meet my requirements. Should I ask a new question or attempt to edit old question?
If your question is very close or essentially the same, and the answers aren't good, either edit it to increase clarity or offer a bounty (which may not work but is worth a try).
If your question is a twist on or a followup to the earlier question, ask a new one and link to the old one as part of your question.
If the existing question is general but you have a specific case not covered by existing answers, offer a bounty for improved answers which cover that case too. Or, if there's a good reason the special case should be considered separately from the general — either your case is too weird, or else the general is too general — then a followup question is appropriate.
In the other direction, if the existing question is very specific and you want to generalize, I suggest looking at the existing answers. If they are steering very strongly towards the general (because the question reasonably was made more specific than necessary, like asking for brand-specific solutions to non-brand-specific problems), then editing the question to also be more general might be okay (used with caution). If the question is specific and the answers are correspondingly targetted, a new question referencing the old one is definitely in order.
You have several options open to you, depending upon how close to the original situation you are in.
Unless you are in exactly the same position as the original asker of the question and you are trying to achieve an identical outcome, my view is you should ask a new question, link back to the original question if you feel it’s relevant and include details about what it is you’re trying to achieve, along with what you’ve tried and why it’s not what you’re after.
Supplying a narrative about what you’ve tried and how successful it has been in a question asked by somebody else feels very wrong to me. If you don’t want to ask a new question, I would suggest that you post your experiences of what you’ve tried as an answer to the original question, rather than an edit to it (assuming what you have tried is relevant to the question). Possible methods that could answer the question, but don’t along with the reason why they cause issues are valid and useful answers, because they can help people decide if they want to avoid that route. It’s also worth noting that adding an answer to the question would bump it to the front page in the same way that editing the question would, so this may also encourage other people to add answers to the question... Particularly when combined with, as suggested by @mattdm, adding a bounty to the question (along with what you’re looking for from it). I would tend to add what you’re looking for as a comment on the question, in addition to putting it as the reason for the bounty, mostly because the bounty reason seems to disappear once the bounty has expired.