@tom the 

something like this

function onChange(control, oldValue, newValue, isLoading, isTemplate) {
    if (isLoading || newValue === '') {
        return;
    }
    if (newValue == '62826bf03710200044e0bfc8bcbe5df1') { // Sys ID = Abel Tuter
        g_form.setValue('category', 'end_user_devices'); // Set Category
        g_form.setValue('short_description', 'This is the end user device'); // Short Description
        g_form.setValue('impact', '2'); // Impact = Medium
        g_form.setValue('urgency', '3'); // Urgency = Low
        g_form.setValue('service_offering', 'fae7e9e7c3635210075edf3d050131a5'); // Set SO = Azure AD Auth
        g_form.setValue('cmdb_ci', '780b8ce8735423002728660c4cf6a7e7'); // Set CI = *MACBOOK-AIR-13

        setTimeout(function() {
            g_form.setValue('subcategory', 'Keyboard'); // Set Subcategory
        }, 3000);
    }
}

If my response helped please mark it correct and close the thread so that it benefits future readers.