Site is designed around Magazine Basic. I was doing some general maintenance and poking last night and hit "Update" on the Magazine Basic theme on the appearance page (I wasn't paying attention; thought I was going to get a "Live Preview").
This update brought the site up to the latest version of Magazine Basic -- but that threw off all the customizations that had been made to the site. So I tried to revert the update back to an older version. Problem is: I didn't know which version I'd updated from.
In the end, I re-uploaded and am now using Magazine Basic 2.7.9 which got the site to look like it did before except that...
Now YouTube embedding doesn't work. When I just paste the YouTube link, it simple shows up in the post as an unlinked link, not as an embedded video. When I use the "old embed" code, the site automatically resizes the video down to a thumbnail width of 160px.
I discovered that if I use the iFrame YouTube embed on a new post then it will embed the video, but...
In all the older posts going back six years, YouTube videos have all been resized down to 160px!
How can I correct this? I've searched the code and the forums and the web for some clue as to what is happening but can't find anything.