I'd like to know how and where exactly i can change all the fonts (Menu, headers, content etc)
I'm not talking about the size, i found this.
I'm talking about the font family.

Thanks,
John

You will have to run a search through template.css file and locate all rules that use Noto Serif, Raleway or Roboto for this template.
Then copy them in your custom.css file and there you can change them with the new ones.
The new ones, if they are google fonts, should be selected through Template parameters.

The Google Web Fonts that you have on the back end are used i guess only for the content correct?
So, if i add them directly to the template manager do i need to change something on custom css?

The selection from the backend is used to load the fonts in the head of your page in order to be located through the CSS afterwards.
You first need to select the fonts from the backend and then do the process in custom.css file to assign in which element you want to load which font-family.