Hi Olufemi,
We can help you, but you will need to do your part (with the Owner’s Manual). This will help you understand the answer... we will use *correct terminology* in our reply. To better understand what we say, it will be your responsibility to get in the habit of doing the same... this is the only way we can effectively communicate.

A program in the MONTAGE is called a “Performance”. A Performance can have one Part and as many as 16 Parts.
As many as eight of the Parts can be linked for simultaneous play from the Keyboard. You will see a green KBD CTRL icon that denotes a Part under Keyboard Control.

A Part is (or can be) an entire instrument.. similar to a Part in the CP.
A Part can be a building block (one component) to create an instrument or even build an ensemble.

To learn to create a Split, you first need to create a Layer. A Layer, at its simplest, is two Parts mapped across all keys.
Then you can learn to Split... a Split is one of those two sounds for the right hand, the other for the left.
Of course, in MONTAGE you can build much more complex Split/Layer combinations — even those with multiple Note regions.

Here’s a basic outline for creating a Layer:
From the HOME screen
Press [CATEGORY SEARCH]
Because you pressed [CATEGORY SEARCH] from the Home screen, you are offered to search for a complete new Performance; “Performance Category Search” appears on the top line.
Set “Bank” = Preset
Set “Attribute” = Single
You will notice that all selections turn green. Green = Single, Blue = Multi.

When learning to Layer we need to start with a green program because, if you start with a blue, you have jumped into a Layer without knowing how it was created! This is why we limit you to Single (green) Performances. You are now viewing every Single Part Performance in the MONTAGE.

Let’s select “Main” = Piano
Select “CFX Stage”
Press [ENTER] to return to the HOME screen

You have selected an instrument for Part 1 — close inspection of that slot shows you that it is mapped across all keys and set to play at all velocities.
Touch the “+” in slot 2... this allows you ADD (or “merge”) a second Part
You are taken to a Search screen labeled “Performance Merge”
Set “Bank” = Preset
Set “Attribute” = Single
Set “Main” = Bass
Set “Sub” = Acoustic
Select “Upright Bass AF1”

Press [ENTER]

You have now successfully created a Layer... both the Piano and the Bass are mapped across all keys (C-2 through G8). When the cursor is highlighting the Performance Name (the upper [COMMON] button is lit, the Sliders will act as Part Volume. Move these to engage real time control over how loud each Part is.

From a Layer to a Split
Yamaha uses the convention where middle “C” is designated as “C3”
Touch the “C-2” Range box for the Piano in Part 1
A pop-in menu appears
Touch the word “Keyboard” to activate Keyboard data entry (turns green when Keyboard entry is active)...
Touch middle “C” to set the Low note for the Piano

Touch the “G8” Range box for the Bass in Part 2
Touch the “B2” to Set the High note for the Bass
Press [EXIT] to deactivate “Keyboard” data entry.

You have now successfully created a Split... Piano above middle “C”, Bass “B2” and below. Simple Splits and Layers can be done without leaving the HOME screen, without hitting Edit.

Additional Programming
Because we have used just two of the available Parts, we can continue programming in this same Performance to accomplish your other requests. Please note: with a Synthesizer like the MONTAGE there are going to be many (many) different ways to proceed. You can place the other instrument sounds you need starting with Part 3.

You could:
_ Place the sound you want to play across all keys in Part 3... then fashion how you wish to transition to it. You could do so with a SCENE button, you could transition with an Assignable Switch, you could ‘morph’ to it with the Super Knob or FC7 Pedal, etc., etc., etc.
_ because as many as eight Parts can be placed under KBD CTRL, this means you could have six other Parts, active, but “in waiting”... meaning you can design when and how they become active. Also because you can directly select PARTs not linked by KBD CTRL, it is possible at anytime to play a sound across all keys and move back to your Split at any time!

Changing the Octaves
If you need to lower or raise the Piano Part or the Bass Part... these are Part Edit parameters. You could first:
_ Select the PART you want to Edit - you do so by touching the screen or pressing the dedicated [PART SELECT 1] button on the right front panel
_ Press [EDIT] -- "Edit - Part 1 - Common" appears across the top of the screen
_ Touch "Part Settings" in column one, > touch "Pitch" in column two
_ Set the "Note Shift" parameter as you require -/+12 = one Octave

Press [PART SELECT 2] and set the "Note Shift" for the Bass.

When you complete your editing you will want STORE your work to the MONTAGE. Press [STORE] you are offered to give your new PERFORMANCE a name (highly recommended - that you name it). And when you touch "Done" it will be stored to the first empty location in your USER BANK. You can store 640 Performances in your USER Bank.

We have a series of articles that will take you through various ways that you can transition between sounds within a single Performance.
MONTAGifying MOTIF article series