How do you undo error in words known

I am on free trial lessons in German. I did something wrong that made the system think I know a page of words I do not know.
Can this be undone.

Highlight all the words and add a LingQ for each word. Than LingQ knows that these are still unknown word for you. It is not as convenient as the usual way, but it will work.

@BrianR - The “I Know All” button is there to update your statistics and tell our system which words you know. The way to use it properly is to LingQ all the words you don’t know or are unsure about and then click that button to make all remaining blue words “Known”. If you click it before you have finished creating LingQs, it isn’t a problem. Just select the words you want to LingQ and you will then be able to create LingQs for them. These words will then be removed from your Known Words total.