God bless you Ruben.
That I understand. Being completely new at this I had no idea I was to highlight the table of contents. Also, I thought that everything would convert over to mobi, including the TOC. Now I know. I guess I was hooked on doing it manually. I'm content to stick with Calibre, and once again I thank you kindly for your patience..
The reason I was unable to locate 'Preferences,' earlier, was because my screen only opened as far as 'Save to Disc.' I was reading 'to locate preferences, look to the far upper right of the toolbar.' But all I saw was Save to Disc. I thought I was truly nuts! Or, I had the wrong version of Calibre. I had no idea it opened further. By a fluke, I opened it further.