Permalink Problem

I have made a new theme for my WP blog. It’s a child theme of Twenty Sixteen. It looks and works great except for one problem.Here is the site.
http://www.openrangeimaging.com/blog/

I developed the new child theme off line on my localhost.My localhost does not like pretty permalinks so in development I use the plain permalinks:
http://www.openrangeimaging.com/blog/?p=123

All of my existing posts and etc were made online with the Custom Structure Permalink:
http://www.openrangeimaging.com/blog/%postname%/

So now if you visit my blog and click on one of the post titles or “continue reading” to go to the single post, it is not displaying correctly. It’s pulling old style info from the previous version child theme I was using. If I log into Dashboard>Setting>Permalinks and select the Custom Structure radio button and then save changes it reverts to having the Post Name radio button above Custom Structure selected. It will not allow me to select the Custom Structure and save that.

If I select the Custom Structure radio button and DO NOT SAVE CHANGES, and just click on visit site, then I can select an individual post and it looks/appears as it should. BUT when I go back to the Permalinks it has once again reverted back to having the Post name radio button selected and then when I visit site and click on individual post it is back to the bad/incorrect display.

I need help getting this configured so I can get that Permalinks Custom Structure http://www.openrangeimaging.com/blog/%postname%/ to stay selected on save. Thanks in advance for any help, I cannot seem to figure out how to get this working correctly.