Change Heading `H1-H6` font

I wish to change the font of the heading from Roboto to Abel, how can I go about it? Thanks for your usual help.

@tobi

Here is how fonts are currently enqueued via functions.php file.

You should change the second part from

Roboto+Slab:400,300,700

to

Abel:400,300,700 Just make sure what font width is available for this font as all fonts are different.

Now you should just change fonts via CSS and and you can do it by adding this code to Theme Options - Other - Custom CSS

h1, h2, h3, h4, h5, h6, .h1, .h2, .h3, .h4, .h5, .h6 {
  font-weight: 700; /* depending on what font width this font supports */
  font-family: 'Abel', sans-serif;
}

Just make sure to change font-weight according to what is available for this font and what you enqueued via functions.php file.