Confused about my credit report, does the 7 years start from when it was delinquent or last reported?

I just got my 3 credit reports. I am confused on the Transunion it said some deliquent accounts would come off 7 years after they were turned in. When I called another experian they said it stated from when it was last reported. Which means that some from 7 years ago where just reported last month. I am very confused??