@dimalifragis Thanks for all your help. Unfortunately, I'm not able to change the images from http to https. The field is greyed out and can't be edited. It's the same for all library items.

I don't know if this is related, but I was also not able to change the wordpress address URL in Settings>General. I discovered this when I tried to use the feature in the latest version of Wordpress to migrate from http to https automatically. I was able to fix this by changing something in the wp-config file in Control Panel (with the help of the wonderful tech support of my host). Now the wordpress address url is https://songwriterjunction.com. It is still greyed out, but at least it is correct. When I run Heath Check there is no suggestion to migrate to https. I'm wondering if there is something else in the php configuration which is disabling the ability to change links to images and audio files. It's not an area I know much about, although this is proving to be a learning experience!

@dimalifragis Thanks for all the help you did provide, even though, as you say, the subject got away from WpForo. I will get back with my host. I moved there from another company who were pretty much all screwed up and may have done this.