How to password protected all sheets at once

Try this... Replace the word protect with Unprotect to un-protect the sheets

Sub ProtectAllSheets()
Dim Ws As Worksheet

Application.ScreenUpdating = False

For Each Ws In ThisWorkbook.Sheets
    Ws.Protect "mypassword"
Next Ws

Application.ScreenUpdating = True

End Sub

Whether by the user interface or by code, they need to be protected one at a time.