Maybe you could try it as below then:
Private Sub Worksheet_Change(ByVal Target As Range)
  Dim wb As Workbook
  Dim YEE As Workbook
  Dim ws As Worksheet
  Dim uCols As Integer
  Dim sMnth As Date
  Dim dRng As Range
  
  Application.EnableEvents = False
  
  For Each wb In Workbooks
    If wb.Name Like "*YEE*call placement*" Then
      Set YEE = wb
      Exit For
    End If
  Next wb
    
  If Target.Address = "$B$4" Then
    For Each ws In YEE.Worksheets
      If ws.Name Like "YEE*MU*" Then
        uCols = ws.UsedRange.Columns.Count
        sMnth = ws.Range("G1").Value
        Set dRng = ws.Range("F:F").Find(Target.Value, , , xlWhole)
        Range("B10:Y10").ClearContents
        ws.Range(ws.Cells(dRng.Row, dRng.Column + 1), ws.Cells(dRng.Row, uCols - 1)).Copy
        Rows(9).Find(sMnth, , , xlWhole).Offset(1).PasteSpecial xlValues
        Application.CutCopyMode = False
        Exit For
      End If
    Next ws
  End If
  
  Application.EnableEvents = True
End Sub