The only way how to do it using autotext - is probably how you are doing. When you create a new text block - draw rectangular (instead of double click) - then your future text will fit into given rectangular and if it's too long - text will jump on second row too.
There is another way, how to solve this. It's very specific GDL coding. I know many people avoiding to program on GDL, but it can help with similar problems a lot. If you interested - let me know, I'll guide you.