QucsStudio uses Octave 3.6.4.
It can easily be replaced by a different version.
The folder QucsStudio\octave\ contains all Octave stuff
and can be replaced by the folder of a later version.
As QucsStudio uses the command line interface (CLI),
the octave\bin\octave-cli.exe file has to be renamed to “octave.exe”.
To get rid of printing the command prompt, the startup script can be modified:
add: PS1(“”); fprintf (” It’s up now!\n\n”);
to the end of the file: octave\share\octave\4.2.1\m\startup\octaverc
If you want to keep the Octave help file (SHIFT+F1 key in the QucsStudio GUI),
copy the file octave\octave-en.chm from the old directory to the new one.
This was tested with Octave 4.2.1, but should work with other releases, too.
Good luck!