The titles on your front page define your site, so a title should always, always best describe what the question is actually about without having to open the thread. If it doesn't, you should edit it; always. It's what helps people with those problems find your site through search.
But someone with a question may not always know the right terminology to accurately describe the problem, so if you can turn a vague title into something more descriptive, go for it. And if you realize a bit of missing context can improve understanding of the question, go ahead and add it. But I wouldn't change the title from a question into an answer, if that was what you were implying in your post.
- Can you help with this problem? ← This is a non-title
- What's wrong with my ice cream? ← Still very poor
- Why does my ice cream melt after I take it out of the freezer? ← PERFECT!
- How to keep ice cream solid by storing it in the freezer ← Don't turn a title into a hint/answer