Some monitors use a small 8-pin IC to store
the settings into. It is a serial flash memory IC.
They have numbers like 24C04. They only cost
about $3 to $4 for the IC.
Some NECs use a 40-pin Weltrend IC that
contains RAM and static memory. It is a
specially programmed CPU that runs the
monitor. It is generally not available to purchase.
I would replace the 8-pin IC and hope that it
fixes the problem.
John