How do I edit existing Global Product attributes to include images

Hello Linda Joyce,

Thanks for reaching out to us. Unfortunately, there has no shortcut, You have to upload images manually for each attribute.

But the good thing is we have auto convert default dropdowns to image type feature if the variation has an image. https://prnt.sc/11mm4ya

You can follow those instructions:
https://getwooplugins.com/documentation/woocommerce-variation-swatches/#enable-auto-image-swatches-without-any-configuration
https://getwooplugins.com/documentation/woocommerce-variation-swatches/#how-to-enable-image-swatches

Thanks