Resetting the cards to New would obviously result in 0 for Learn and Due – because you’ve reset the cards to New! But it doesn’t erase the count of reviews that you’ve already completed today. So if you already introduced 40 New cards today, as you found, you’ll need to increase your limit. Custom Study is one possibility – the “Today only” limit in Deck Options is probably easier. Deck Options - Anki Manual
That add-on does the “other half” of the job – erases the review history, but without changing the status of the cards. If what you want is pristine New cards that show no indication of ever having been studied before, you should reset them to New, and then remove their history with the add-on.
I’ll just note for you that doing either of these things should be a rare occurrence. You will normally want your cards to accumulate review history so that they will be scheduled for Review accurately.