I used to be able to click the checkbox button and insert one wherever I liked. If my thoughts included a "to do" task, I'd put a checkbox wherever that though happened to be written.
Now when I click the checkbox button it always turns the current line into a checkable item with the checkbox at the far left.
Thank goodness I can copy and paste one of my existing midsentence checkboxes in order to create more of its kind, but I wish the functionality were still there in the web client. (At least it hasn't been taken from the iOS app...)