Timer Macro Causes WB To Save While Closed

I have a macro that starts a timer when the workbook is first opened. When the timer hits "0", the workbook saves and closes. Works fine. I also have it where when the workbook is "Read-Only", the timer does not trigger the "save and close" of the macro. If I have another instance of excel open, and close the macro enabled WB, the macro still runs, even though the WB I have open now has no macros in it.

It will still run the "save and close" function of the original WB macro.

Is there anything I can add to it to make it specific to that WB with the timer macro? Even when it's closed without saving, it still runs the save if there is another excel sheet open.

Any help would be greatly appreciated!

Thank you in advance!

Dim ResetTime As Date

Sub StartTimer()
    ResetTime = Now + TimeValue("00:00:30") ' Set initial timer for 2 minutes
    Application.OnTime ResetTime, "CloseWorkbook" ' Schedule closing the workbook at the specified time
End Sub

Sub ResetTimer()
    On Error Resume Next
    Application.OnTime ResetTime, "CloseWorkbook", , False ' Cancel previously scheduled close event
    ResetTime = Now + TimeValue("00:00:30") ' Reset timer for another 2 minutes
    Application.OnTime ResetTime, "CloseWorkbook" ' Schedule closing the workbook again
End Sub

Sub Workbook_Open()
    StartTimer ' Start the timer when the workbook is opened
End Sub

Sub Workbook_SheetChange(ByVal Sh As Object, ByVal Target As Range)
    ResetTimer ' Reset the timer when any activity is detected
End Sub

Public Sub StartTimer()
    If Not TimerStarted Then
        Application.OnTime Now + TimeValue("00:00:30"), "CloseWorkbook"
            TimerStarted = True
        End If
End Sub
Public Sub CloseWorkbook()
    If Now > LastActivity + TimeValue("00:00:30") Then
    On Error Resume Next
    If Not ThisWorkbook.ReadOnly Then
        ThisWorkbook.Save
    End If
    If Not ThisWorkbook.ReadOnly Then
        ThisWorkbook.Close
    End If
SaveChanges = False
    Else
        StartTimer
    End If
End Sub