Sub ChangeCommentName()
Dim xWs As Worksheet, xComment As Comment, oldName As String
Dim newName As String, xTitleId, x
xTitleId = "KutoolsforExcel"
oldName = InputBox("Old Name", xTitleId, Application.UserName)
newName = InputBox("New Name", xTitleId, "")
For Each xWs In Application.ActiveWorkbook.Worksheets
For Each xComment In xWs.Comments
x = xComment.Shape.TextFrame.Characters.Text
x = Replace(x, oldName, newName, , 1, vbTextCompare)
xComment.Text x
Next
Next
End Sub