USBRIO-7845R. Analog Output settling time

hi.

i am using USBRIO-7845.

i have confussion about it ANALOG OUTPUT SETTLING TIME. According to data sheet, changing of LSB, its settling time cab be vary from 7us to 1.5us for 20V step.

in software, how i can change this LSB stuff. the settling time which i am achiveing is nearly 10us. i can compromise on accouracy but cant on Settling time

Regards