I have created a child theme of moesia-pro-ii. The moesia theme has a widget folder with a php file named "fp-latest-news". In default this widget uses h4 tags. I want to change the h4 to h3 tags in the child theme. All I know so far is, that I have to add something to the functions.php of the child theme. Everything I tried so far(which I found on google) didn't work for that case.

Does anybody know how to solve this case?