To speed-up all, use custom function. Go to VBE (Tools>Macro>Visual Basic Editor), add module to your VBProject and paste here:
Function ChangeComment(rng1 As Range, sTxt As String)
Application.Volatile
rng1.Comment.Text sTxt
End Function
Suppose you have text in A1 and need a comment in B1. Add comment to B1 and format it. In C1 add formula: =ChangeComment(B1,A1)
For texts in column A, copy down cells B1:C1, to get comments in column B1. The comments should contain text from cells from column A. Now you can delete formulas in column C, text in comments will remain.
combo