Font Size Issues in Clean Fotografie Pro theme

Hi Guys, I've just purchased this theme and applied it to an existing site. The problem I'm experiencing is that all the headers are waaaay too big and the fonts are terrible. When I go into the theme customisation and choose different font family options, as soon as I save and publish, the changes are all lost and it reverts back to the previous fonts again. The other thing is that there are no options I can find to nominate font sizes anywhere in the theme. The theme is great but the fonts are a disaster.