Changing the marker style on a chart

Hi

I have a line chart with three series on it. Can vba change the marker style of all three lines at once? Or will I have to loop through using 'For Each'?

If the only answer is 'For Each' then please could I get some guidance on how to do this with SeriesCollection 1-3.

Dim AnnualChart As Object

Set AnnualChart = ActiveSheet.Shapes("AnnualChart").Chart

      If ActiveSheet.Range("A11").Value2 = "January"
      
         AnnualChart.SeriesCollection(1).MarkerStyle = xlMarkerStyleSquare

      End If

Many thanks

James