How may I edit spellings in a question? Once it is answered, there is no option available to change the words.
You can't do that.
Regular contributors cannot edit questions that have already been answered, only mods can do that (and Heroes in their respective subjects).
This is a safety measure that the team implemented a long time ago to prevent users from messing with questions that have already been answered mostly so that we won't have to track these edits like we do with edits made to answers.
So basically, the fact that nobody except a few people can edit questions after they have been answered saves us the time of checking every made every edit made to an answered question to make sure that it's not making the question and the answer incompatible.
There is a chance that this will change at some point in the future, but that's how the system works at the moment.
PS: I edited that question for you! :)