I want to sort 2 different columns automatically in one sheet

I am currently using the the formula
Private Sub Worksheet_Change(ByVal Target As Range)
'Updateby Extendoffice
On Error Resume Next
If Application.Intersect(Target, Application.Columns(1)) Is Nothing Then Exit Sub
If Target.Count > 1 Then Exit Sub
Range("A1").Sort Key1:=Range("A2"), Order1:=xlAscending, Header:=xlYes, _
OrderCustom:=1, MatchCase:=False, Orientation:=xlTopToBottom
End Sub

This only works to auto sort column A in the worksheet function not in the module part. I want to then use this same formula to auto sort column B as a secondary sort. Can someone give me some instructions regarding this.
Thank you