Header Fonts Won't Change

Hi,
I used the change font option in Styling and changed my font to Oswald. It worked fine for a few days. Then suddenly out of nowhere, it changed back to the default font. I tried changing to another font type (tried almost all the fonts in list provided) using the same Styling options but no font works. It still shows the default font. I just can’t seem to change the heading fonts to anything else other than what is already displayed. It seems stuck for some reason.

I’ve also tried clearing my browser caches and accessing it through different computers and browsers. No change.

Not sure what’s the problem. Please advise. Thanks.