Changing the font in widget

Hello,
I have been trying to change the font in the sidebar widget that reads “Instagram” (as well as the rest of the headings in the widgetized area. I have inspected these, which shows it is pulling info from H4. I tried to change H4 font through Highend options, of course, but it did not chnage. In fact, looking further into the inspect element window, the font directive seems to have a strike through. (?)
I am not proficient at coding, but I am trying to follow.
I have the latest version of this theme, latest version of Wp, and have included two screenshots. One will include the “inspect element” of “Instagram” text in gold.