In Kitprog manual is written to press the switch for more than 5 seconds to change the mode.
That's exactly what I'm trying to avoid, because many times happen that I disconnect the Kitprog from PC, then connect it again, and it shows again as Mass Storage. So again I need to press for 5 seconds.
I want to disable this mode permanently.
You can't disable the mass storage mode from current version of Kitprog.You can go to older version of Kitprog, for that you have to upgrade Firmware of Kitprog using older version of PSoC Programmer.
But ,it is always recommended to have newer version for improved software.