Questions can never be edited, but you should have an Update option. Answers can be edited until a Best Answer has been selected. At that point, no answers can be changed (you can just set your profile to Anonymous or remove it from being Anonymous).
If you are trying to update a recent question you posted or edit an answer to a question with no BA yet, and you cannot do that, then it could be a glitch with the site. Try a different device or browser just to see if it's affecting your account no matter how you access YA. The site is working as per usual for me, so far, today.