We used to recommend the plugin Easy Google fonts for changing our theme fonts.
We now recommend the choice of 2 different FREE plugins that allow you to edit the fonts in a visual interface with no code selectors really required.
OPTION 1: Font plugin
The most simple of the 2 is called Font.
Simple search for "font" in the Add New plugin panel.
1. Install and activate the plugin.
2. Go to Dashboard > Appearance > Fonts. Follow the instructions on the screen. They even provide a link to open your home page in a new window.
3. In the new homepage window, in the Admin bar you will see a new link Font Settings. Click on the link to open the font editor.
4. A box with a white hand that says Pick any element will appear. Click on the box. A red box that says Stop Selecting will appear.
5. Hover over the element you want to edit. A dotted blue box will appear around it.
6. Left click and a gray box will appear. You will be asked to give your selection a name (to save your selection for future editing). Give it a name and click the OK button.
7. Now you will be able to edit this selection using the tool bar at the top.
8. To change the font family, click on the white Choose a font button. You will be able to choose from Fontsforweb.com fonts or Uploaded fonts.
9. To change the font size, type a px number in the box or use the slider to the right.
10. You can also change the color by opening the color picker by clicking on the pink box.
11. Once you are done with your selections, click the blue Save button.
OPTION 2: MICROTHEMER
This plugin is a tag bit more complicated but the interface is much nicer.
It's called Microthemer Lite. Just enter that in the plugin search to add a new plugin.
Once you install, you will have a new link on your WordPress admin panel, Microthemer.
Under the Microthemer menu, pick the Microthemer sub option.
A "live" version of your site will open with a tool bar at the top.
The first thing you need to do is create a Selector. To create a Selector, hover your pointer over whatever element you want to edit and double-click. I am going to edit the post labels.
A side menu will open. Under Targeting it will show a list of all the CSS selectors that apply to the element you selected. Generally ignore the ones with numbers. In this case, we want to pick the one "span.cat a" - that is the general selector for the post labels. So click on that selector from the list.
HINT: To make sure you are picking the right selector, turn ON highlighting by clicking on the Toggle highlighting option.
Once you have highlighting on and you select a Selector option from the Targeting list, it will highlight ALL the elements you will be editing. So, in this case, when you click on span.cat a and then scroll down the page you will see ALL the category labels are highlighted.
At the top of the side menu, give your Selector a name and then pick a folder to save it to. Click the arrow to save it to a default folder or make your own. I called my Selector Post Category and selected the Posts General from the folder list. Then click the green selector at the bottom of the menu.
you are ready to edit the category labels. There is a tool bar that
shows the default settings of what you've selected. You can choose a
font from the drop down menu. It includes all the Google Fonts plus
more. I choose Montserrat from the Google list (click the Use this font link under the font name to add it).
You can change the color with this plugin but of course you can already change most of the theme colors in the customizer. You can also change the font size, line height, font weight (bold or unbold), italics, underline, and force caps or no caps. So I made mine, 700 weight (bold), italic, underlined and all caps.
When you're done, click the little disc icon at the top to Save your changes.
If you need to revisit a Selector to re-edit it, click on the folder icon
near the top left corner. A drop down of all the folders will appear.
Click on the arrow next to the folder you assigned your Selector to. In
my case, Posts General. Then I can click on my Post Category selector and edit the font again.
If you ever need to reset your settings, click on the Undo icon near the top left. Then select one of the options from the drop down to reset to default styles.