For this question, I refer to the post below to clarify myself:
Why is my conditional format offset when added by VBA?
In many, many posts I see these days, OP\'
There are a few methods in Excel that require Activate or ActiveSheet/ActiveWorkbook etc as I've been caught with a gotchas on occasion. The only one I can remember at the moment is the zoom property. Zoom affects only the sheet that's currently active in the window so to zoom all sheets you would need something like
Sub SetZoom()
Dim ws As Worksheet
Application.screenupdating = false
For Each ws In Worksheets
ws.Select
ActiveWindow.Zoom = 80
Next ws
Application.screenupdating = true
End Sub