No, not exactly. When you ask a question you can add Bonus Chips (BCs) to highlight that question. The amount you choose to use is fixed at that point.
Currently you need to spend a minimum of 250 BCs to highlight for one hour.
If you spend the minimum of 250 BCs then the question will remain highlighted forever BUT it only keeps the sort order preference for the total hours paid for. 500 would get you 2 hours sort preference, 1000 would give you 4hrs etc.
Sort order preference means that the Question will remain on the top of the list even if another question is asked after it. The only time that isn't true is if another person asks a question which has more hours of highlighting, then it will go above your question.
But if you really want to make sure it stays on top, you can then edit your question to add more BCs and keep it at the top of the list.
Don't forget the other reason why you want to Highlight Questions! 50% of the BCs used will become a reward (or bounty) for the person who has the best answer. This gives other members of Poqery a real incentive to make sure they answer your question to the best of their ability.