I think you are using Arial 12 pt, bold for the title of the thread and regular for the body. I can't exactly determine the old font, but it was more like 10 pt. It just seemed more readable to me. Note, in typing this response, it appears to be 10 pt as I type, but 12 pt once posted.

Windows 10 desktop with 27" monitor, it that makes a difference.

(Whether it's changed back or not, I appreciate the response - thanks)