Automatically Trigger Event when Cell Changes

Hi, I'm trying to create a drop-down menu of sorts that is available in every page of the worksheet. I have the value of every page's drop down box linked to a hidden spreadsheet that uses a vlookup table to give a value based off of what "menu option" is chosen with the "default" option yielding a value of 0. I have the sum of all of the pages' numerical values in a cell on this spreadsheet and would like to create a macro that triggers whenever this cell (containing the sum) is not equal to 0. The cell that is going to be triggering the macro when not equal to 0 will be on the hidden page (MACRS Loans) and therefore not active. The Run Reset_menu at the bottom of the code runs a macro that changes all of the drop down boxes back to their default value after the page is changed in order to reset the macro. Below is what I have so far in VB, the macro works when manually executed but not automatically when the cell is changed. Any help would be much appreciated, Thanks!

Private Sub Menu(ByVal Target As Range)
If Not Application.Intersect(Target, Sheets("MACRS Loans").Range("C12").Value <> 0) Is Nothing Then
    Application.EnableEvents = False
Select Case Sheets("MACRS Loans").Range("C12")
    Case 2
        Sheets("Home Page").Select
    Case 3
        Sheets("Taxes").Select
    Case 4
        Sheets("Loans").Select
    Case 5
        Sheets("Compounding").Select
    Case 6
        Sheets("Bonds").Select
    Case 7
        Sheets("Continuous Compounding").Select
    Case 8
        Sheets("WACC MARR & Cost of Capital").Select
    Case 9
        Sheets("Capitalized Cost").Select
    Case 10
        Sheets("Discounted Payback Period").Select
    Case 11
        Sheets("Depreciation").Select
    Case 12
        Sheets("Corporate Tax Rate").Select
    Case 13
        Sheets("MACRS-GDS").Select
    Case 14
        Sheets("Inflation").Select
    Case 15
        Sheets("Duration").Select
    Case 16
        Sheets("Home Page").Select
        Run "Clear_all"
    End Select
    Run "Reset_menu"
    Application.EnableEvents = True
    
End If
Application.EnableEvents = True
End Sub