Credit Karma review: Credit changes

All i did was disputed an accurrate account that went to collections more than a year ago. It said it was resolved an approved and i should see changes by April 15. Today I checked and it has significantly went down from 587 to 415. Can you tell me what happend? I also tried to check if I was could be approved for a secure debit card I don't think that hard inquiry would have knocked my points that far down I heard also that if I was to dispute a collection account that that wouldn't have brought my score down either just wondering how I can fix it and what the problem is why it drops so low if you can help me with that please