Heres the definition of heritability:

(HAYR-ih-tuh-BIH-lih-tee) The proportion of variation in a population trait that can be attributed to inherited genetic factors.

The study title is saying that heritability INCREASES with age: as you age your IQ is more closely correlated to the IQ of your parents from whom you inherited your genes from.

>As you point out a couple of comments later, genes don't change with age.

Your genes dont change but the correlation between you and your parents IQ does.