Cant Change Font Size

Hi there! I’ve changed my site’s heading font to Amatic by using google fonts and Sydney’s customization view. I cant seem to make the font size bigger though for the Headline as well as the Sub menu titles in my content. I was only able to increase the font size of my Content titles such as “About Us, Our Work, etc.” through customization of H3. Others don’t seem to work.

Pls advise. Thanks!

by the way, this is my site