A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
Use this in the codemodule of the ThisWorkbook object of your Personal.xlsb: If you don't use a Personal macro library, create one by starting to record a macro and choosing to store the macro in "Personal macro workbook" and Excel will create it for you.
Private Sub Workbook_Open()
Application.ActiveWindow.WindowState = xlMaximized
End Sub