Well it’s not as straightforward as I hoped. I tried to follow the directions of various experts that I googled without luck. I did begin to see the differences between a regular post page with its attachments settings feature and the more Spartan design of the attachment post for the gallery images. Ideally I would like to give the attachment page more of the features of a regular post page, i.e., the ability to link to a custom URL and To control the size and placement of the image.
Speaking as a code challenged individual, Am I on the right track to think that a child theme should be created to house a new/altered template for the attachment pages for the gallery images?