Macro to loop through all sheets and delete unwanted columns

I have the following macro which opens all the Excel files within a given folder, loops through them all and deletes columns G to N, then it re-saves each of the files.

It runs without error, but when I opened the Excel files to check that the columns had been deleted correctly, I noticed that the macro had only worked for one tab per file (Sheet1). However, I need it to loop through all the tabs in each of the files to delete the unwanted columns. The tab names are not the same in all the spreadsheet files.

I thought that the For Each Worksheet In ActiveWorkbook.Worksheets command would loop through all of the tabs within each of the open files?

How would I fix the macro so that it works for every tab?

Sub OpenandchangeAllFiles()
    Dim fList() As String
    Dim fName As String
    Dim fPath As String
    Dim I As Integer
    'This folder will be searched for Excel files
    fPath = "C:\My Documents"
    'build a list of the files
    fName = Dir(fPath & "*.xls")
    While fName <> ""
        'add fName To the list
        I = I + 1
        ReDim Preserve fList(1 To I)
        fList(I) = fName
        'get Next filename
        fName = Dir()
    Wend
    'see If any files were found
    If I = 0 Then
         MsgBox "No files found"
        Exit Sub
    End If
 
    'cycle through the list And Open
    For I = 1 To UBound(fList)
        Workbooks.Open fPath & fList(I)
        'select all  worksheets In turn
        For Each Worksheet In ActiveWorkbook.Worksheets
            'delete all unwanted columns
            Columns("G:N").Select
            Selection.Delete Shift:=xlToLeft
        Next 'next worksheet
        'close &  save  changes To workbook
        ActiveWorkbook.Close True
    Next 'next workbook
 
    MsgBox "All unwanted columns have now been deleted from all the spreadsheets."
End Sub