After reading the manual a little confused as to saving edited voices to a user bank
all my other keyboard have a 128 user bank

You can store your edits to USER Voices to the MX's bank of 128 USER locations.

It has 128 Performance locations and it has 128 User Voice locations. These are separate banks. Voices can be used in any of the 16 PARTS of a PERFORMANCE.

When you call up a PERFORMANCE, you are actually recalling 16 Voices (each in a PART).
Press [PART SELECT] right front panel. Now the buttons allow you to select PARTs 1 through 16 of the current PERFORMANCE.
You can link and play PARTs 1 and 2 together.... while PART 3-16 are available for individual selection or for use with an external sequencer (DAW) like Cubase AI.

Hint: when the [PART SELECT] button is lit, you read what is underneath the buttons
When PART SELECT is not lit you are in CATEGORY mode where the item written above the button applies. (This will help you navigate the system).

Page 17 of the Reference Manual will give you an overview of the MX architecture.

When a USER VOICE is stored it will be placed in one of the MX Voice CATEGORIES.
If for example you edited a Synth Lead sound, your USER creation would be found in the LIST under Synth Lead Category. The letter "U" will identify it as a USER Voice.

Reference Manual page 50 VOICE EDIT will take you through the process of making, storing and finding USER Voices. If you have further questions post back here.

don't see any category buttons in LCD in edit mode?

The CATEGORY buttons on the right front panel Piano, Keyboard, Organ, Bass, Guitar, etc., etc.,

in the screen you will see abbreviations: AP = Acoustic Pianos, KB = Keyboards, OR = Organs, BA = Bass, etc

Call up the first PERFORMANCE...
Press the [SELECT] button to turn its light OFF..

AP: ConcertGrand (Acoustic Piano)
STR: Amb Pizza (String Ambient Pizzicato)

found it

hopefully last question and thanks for your input

Im trying to save a layer in the AP category ie Piano on top Ens Mix Str on bottom
only saved half????

You are trying to save a PERFORMANCE... Not a VOICE (by definition a Voice is a single sound)... any "layer" is automatically a PERFORMANCE.

Press [SHIFT] + [SELECT] to do a QUICK RESET... this places you in a state ready to build a Performance - it defaults to the AP: Concert Grand (as a single).
Call up the Piano that you want to use.
Press the [LAYER] button, it will light
The cursor will move down to PART 2 in the screen

You can now select the category you want - it actually defaults to strings (because if you ask 100 keyboard players what they want to layer with acoustic piano 95 of them will say Strings).

The STRING Category button is already lit... you can now search through the STRING Category for the "Ens Mix" Voice for PART 2 - You can use the Data Dial or the INC/DEC buttons to scroll through the various String Category Voices. As mentioned previously, if you create a USER STRING Voice it will appear at the very end of the STR Category.

NAME and STORE your PERFORMANCE... you will need to OVERWRITE one of the 128 Factory PERFORMANCES.
When you press [STORE] you are offered any of the 128 PERFORMANCE locations.

Thanks I really appreciate your help
Love this keyboard but a little difficult to edit compared to all
my other keyboards which have a user bank

The MX has a USER Bank. I thought we established that. ?

One for PERFORMANCEs (128)
One for VOICES (128)

I meant compared to my Korg Krome or Nord Electro 5 where the user is easy to find and edit

Thanks again