The Assign Switch 1 and Assign Switch 2 have dual functions, unlike many of the other controllers they have a dedicated function involving the AWM2 Element's XA CONTROL (Expanded Articulation Control). They can be used to dynamically turn On/Off individual Elements. Typically, the programmer will leave a clue to such use in the Performance name. If you see the letters "AF" in the name this is indication that the Assign Switch is used for the XA CONTROL function. The other role is as an assignable controller within the Control Assign matrix for general use (which you can view using the controller "Display Filter".

So there are actual two places to look when seeking to understand how these two Switches are used within any Part.

If the Part is AWM2 be sure to check the Oscillator screen
Press [EDIT]
Press the [PART SELECT 1-8] button to view the Part's parameter data
Select Element 1 (you can do so in the screen or with the number 1 button on the third row of 8 right front panel buttons)
Touch "Osc/Tune"
Here you can view what, if anything, is assigned (XA CONTROL) to the switches "A.Sw1 On", "A.Sw2 On", or "A.Sw Off"
Check each active Element...

The other place is within the Control Assign box
From EDIT
Press [PART SELECT 1-8] button to view the Part's parameters
Select "Common" (blue) lower left corner of the screen (or press the lower [COMMON] button on the right front panel)
Touch "Mod/Control" > "Control Assign"
Set the "Auto Select" function On (green)
Press the [Assign Switch 1] to view any assigned parameters
Press the [Assign Switch 2] to view its assigned parameters, if any.

Alternate Method
From the HOME screen touch "Motion Control" > "Overview" (you can also get there by pressing [SHIFT]+[PERFORMANCE(Home)])
You can isolate just Controller (magenta) and view the assignment, if any, for Common and any of the 16 Parts. Below I show viewing PART 6's Controller Assignments:

Once you see that Assign Switch 1 is used, as shown in Part 6, you can take the shortcut "Edit Part 6 Control settings" to go directly to the Control Assign area for this PART; use "Auto Select" (green), press [AsgnSw1] to view the parameter(s) assigned to the Switch.

Thanks a lot!!!!