If you get Rooster Observer (premium) then you can open any lesson and see the “known” words, and then you can go through and change the status of words that don’t belong in that list.
Without that browser addon, you can go to a lesson and just open the sidebar on the right of the page to see all the words in the lesson, and you can then either (1) find the words in the lesson and change their status or (2) edit the current sentence, adding to the end of the sentence all the words whose status you want to change, save your changes, and then just click each word to change its status.
Edited to add:
If you recently joined, your known words aren’t that high yet, so you can go to:
https://www.lingq.com/api/languages/ko/known-words/?page=1&page_size=100&cardsTranslitFormat=list
Change “ko” to whatever your language abbreviation is. That will give you a list. I would just copy/paste this list into a lesson and then you can click on each word to change the status if desired.
Good luck!