I have the same problem, but adding the line
export QT_AUTO_SCREEN_SCALE_FACTOR=0
to the file
/opt/local/CloudBerry Backup/bin/cbbGUI
did not change the screen size.
Additionally, when I close the application by right-clicking on the favorites icon, and clicking Quit, it crashes the kernel and all my applications are closed (fast command line screen mentions kernel error - I'm a linux novice).
Did I do something wrong? I had to chmod o-w cbbGUI to edit the file.