However, the problem with this is that I have external links pointing to other websites which links I have to keep http. (There is no https version of those websites.)
To resolve this problem, I set the AdminTools / SEO & Link Tools / Tools to NO.
This solves the issue with the external links, but causes a different problem: the https link which loads the Google fonts in the index file changes from https to http and the Google fonts do not load.
Interestingly, I see in the source code, that some of the https external links remain https (eg. Youtube, Facebook, Flickr)
Some examples
Innovationsgolf.com:
google fonts changes from https to http,
Facebook, Twitter remain https
exquison.com:
google fonts, and the fast.fonts script change from https to http
Regards,
Tom