If you want to edit your to-do, you can click to the three dots that appear when you hover over a to-do.
Then, click to "Edit" and it will take you to you to-do detail where you'll be able to not only edit your to-do but also take notes, bookmark, time track, add subtasks and do much more.
FAQ
Can I edit a to-do after it's completed?
Yes, you can edit your completed to-do by marking uncompleted.