Getting featured image to resize on mobile

The setting for this depends primarily on the theme you are using. A link to your page could show which theme you are using. Your theme’s support team would also be best placed to help you with your question.

Thanks, the original theme is Ascent.

Here is the page: https://ascentdentalcare.ca/about/

I’m try to keep the header picture looking the same whether on web or mobile!

I’m a bit confused about the theme. It’s called Ascent, but is probably based on Underscore (and is therefore not the free theme of the same name). I could recommend the following CSS as a possible solution:

@media only screen and (max-width: 667px) {
 header.entry-header {
  background-size: cover;
  background-position: right;
 }
}

You could balance the background positioning even better yourself.

If that doesn’t work, I would recommend contacting Underscore support.