The interval of the high limit on rate-of-change alarm and lower limit on rate-of-change alarm is determined by multiplying the scan interval by the number of times sampled. Where do you set the scan interval?

To set the scan interval, press MENU (to switch to setting mode), hold down FUNC for 3 seconds (to switch to basic setting mode), and select the Menu tab > A/D, Memory.
For details, see section 3.1, “Setting the Scan Interval and the Integration Time of the A/D Converter” in the user's manual (IM 04L41B01-01E).