when you are inserting text, on the menu bar there is a number with carriage return arrow going thru it.
The number its set at, and if its highlighted (selected) represents how many blank lines you get every time you
enter text.
What you need to do is dehighlight (unselect) that selection box. Then you can add more text to the same line.
you will still be limited to the 80 characters before you have to hit enter, but then you can continue in the same line of text (subtext).
Then when you want to go to the next line reselect the menu pick with the number in it.