SiteOrigin Slider Widget Image Size

I’m using the slider widget inside a PageBuilder block on a widget on my site.

The actual width of the slider inside this widget is 290px.

However, it’s forcing it to load & display the default 960×640 pixel source images, which then get scaled down to 290×191 pixels. Visually, it’s great, it’s exactly what I want.

However, is there a way I can have it load the “medium” (300×200) image size instead of the 960×640 full size images in order to optimise bandwidth and speed up page loads for site visitors?

Thank you! :)