Set column width in VBA

[Titian]

I have 21 worksheets in a workbook and I can alter the zoom ratio with this code

ActiveWorkbook.Sheets.Select
    ActiveWindow.Zoom = 80

however I also want to change column widths on all worksheets BUT this will not work

ActiveWorkbook.Sheets.Select
    Sheets("Fred").Activate
    Columns("D:D").EntireColumn.AutoFit
    Columns("F:F").EntireColumn.AutoFit
    Columns("I:I").EntireColumn.AutoFit
    Sheets("Bill").Activate

Where am I going wrong, please?

 

[VoG]

Perhaps like this

Dim ws As Worksheet
For Each ws In ActiveWorkbook.Worksheets
    With ws
        .Columns("D").AutoFit
        .Columns("F").AutoFit
        .Columns("I").AutoFit
    End With
Next ws

 

[Titian]

Thanks Peter, that works fine.

My trial and error method clearly means I am lacking knowledge of some fundamental rules as to how this ought to be accomplished.