VBA code that you can use to protect all worksheets in Excel.
VBA Code:
Sub ProtectAllWorksheets()
Dim ws As Worksheet
' Loop through each worksheet in the workbook
For Each ws In ThisWorkbook.Worksheets
' Protect the worksheet
ws.Protect
Next ws
' Inform the user that all worksheets have been protected
MsgBox "All worksheets have been protected!"
End Sub