It’s set on the machine console, along with the manual speed.
On my KT332N, Enter puts the edit cursor on the Speed field. Down arrow to the Power field, Enter to edit it, another Enter to edit the Max power field, then you’re in the UI hellscape of numeric entry.
When you’re done with that, set the pulse duration to about 30 ms through the Menu → Laser dialog.
A 30 ms pulse at 30% power lightly toasts posterboard during mirror alignment and pokes pinholes in chipboard when aligning the red-dot laser on the platform.