Select a CC Number not used by a MODX Control. You can view what MODX is set to send/respond to:
From HOME
Press [EDIT]
Touch “Control” > “Control Number”
Here you can see what this Performances is set to use as far as cc numbers... choose anything other than these.
The FS ASSIGN screen can be accessed from this screen by tapping the “MIDI Settings” shortcut box.

Thanks BM,

I set FS Assign to 30
But is this setting a global setting or an individual setting for each performance.
As I changed performances I found the modifyed setting in every performance.

FS ASSIGN is a global assignment.

This tutorial reinforces the global / system-level of the FS assign feature. https://www.yamahasynth.com/modx-category/mastering-modx-modx-midi-settings-explained (see "8 - GLOBAL SETTINGS FOR FS ASSIGN, SUPER KNOB CC, SCENE CC" )

Generally, the UTILITY menu items are system-level which affect all Performances globally. The quick setup templates change mostly system-level features but also affect some performance-level parameters. This is about the only exception to the rule-of-thumb that UTILITY is where system-wide global settings are.

You should know you're editing a Performance-level parameter because you've gotten there either by touching the Performance name and editing the common/audio (Performance) settings or touching one of the PARTs and now editing the PART parameters.

There may be "wormholes" from the Performance-level parameters to the system-level. These are simply shortcuts to going to the UTILITY menu. The "MIDI Settings" button is one of these wormholes.

Notice in the link provided for the tutorial has a picture of the MIDI Settings area. At the upper-left is the title of the menu "Utility". This tells you you're not editing a Performance but rather the system parameters. In contrast, the title may be "Edit - Common/Audio" - which is a Performance-wide area. Parameters in this screen affect the entire Performance. Or, the title may start with "Edit - Part X" (where X is a PART number 1-16). These screens the parameters are also affecting the Performance - but apply to only one of the PARTs within the Performance (and do not affect other PARTs).