The documents in LaTeX or in AmsTeX or in Beamer are processed by pdfLatex hence there are in PDF  by default.
You can have them in DVI format by default by use of the menu commands:
Preferences/jPreTeX Preferences
then choose put away the case
"Compile avec pdfLatex par defaut".
If you want to use DVI occasionally, use the menu commands:
    TeX/Translate in TeX B&W
followed by:
    TeX/Compile by TeX.
But then you have to use a converter to proceed with the DVI file.