Option Explicit
Sub CaiChanXinhXinh()
Dim ws As Worksheet
Dim strUserName As String
strUserName = Application.UserName
For Each ws In ThisWorkbook.Worksheets
With ws.PageSetup
'.LeftFooter = strUserName '1
'.CenterFooter = strUserName '2
.RightFooter = strUserName '3
End With
Next ws
End Sub