Use this macro from Debra Dalgleish.

Sub ResetComments()
Dim cmt As Comment
For Each cmt In ActiveSheet.Comments
  cmt.Shape.Top = cmt.Parent.Top + 5
  cmt.Shape.Left = _
     cmt.Parent.Offset(0, 1).Left + 5
Next
End Sub

If not familiar with VBA and macros, see David McRitchie's site for more on
"getting started".

http://www.mvps.org/dmcritchie/excel/getstarted.htm

In the meantime..........

First...create a backup copy of your original workbook.

To create a General Module, hit ALT + F11 to open the Visual Basic Editor.

Hit CRTL + r to open Project Explorer.

Find your workbook/project and select it.

Right-click and Insert>Module.  Paste the code in there.  Save the
workbook and hit ALT + Q to return to your workbook.

Run or edit the macro by going to Tool>Macro>Macros.

You can also assign this macro to a button or a shortcut key combo.

Gord Dibben  MS Excel MVP