Why can't I edit a To Do item?

Once a to do item is completed, editing the item becomes locked. This is to prevent changes that could be confusing to others in the village once an item has been completed.

If you want to make changes to a completed to do item, you'll need to mark the item as incomplete again by un-checking the item. You'll also be able to add a comment to let everyone know why you're making a to do item incomplete again.