There are occasions that I want to change a word back to a new word.
One example is a misspelled word. If I accidently LingQ a misspelled word, now I have a misspelled word in my vocabulary list. If I ‘remove’ or ‘ignore’ the word, the misspelled word becomes ‘white’ and it would be better if it appeared in ‘blue’ as a new word, since it isn’t a word at all and needs to be corrected.
You can never change a word back to the status of a new word once you have done anything with it. Such a process would be against the second law of thermodynamics.
Access to the list of known words and making a known word “unknown” again has often been wished by the members. But for unknown reasons LingQ always refuses these requests.