If you want to reset all of your vocabulary and stats. I believe you can reset the language overall from settings. This would make everything blue.
You can’t otherwise make them blue (as far as I know), but you can assign it another status (1-4 or known) or set it to ignore.
I love LingQ, but it is frustrating that they are so stubborn about providing a way to adjust the known and ignored words lists easier, as we can with the other statuses.
You can get a list of all your known words through the api by using this url:
https://www.lingq.com/api/languages/hi/known-words/
You’ll want to select “pretty print” because of the non-roman script. Given that you are not so far along, you could take that text and import as a lesson and make your adjustments manually to reset the ones that are not “known” for you to “1”. This can be done from within the lesson, or you can do it from “Manage LingQs” or filtering to that lesson in the vocab tab.
It isn’t pretty, but you may be able achieve what you want to this way.
Good luck!