On all of our instruments, the "default program" that loads at power up is set to whatever the current program is when the Globals menu is entered/exited. We do this to avoid unnecessary writes to flash memory. For the last selected program to always load on power-up, you would need to write to flash every time you change programs. This may not seem like a lot, but over the course of decades of use, this drastically reduces writes to flash, and therefore prolongs the life of the flash IC significantly. We build instruments with longevity in mind.