Option Explicit
Sub ChangeFormula()
Dim varWorksheet As Worksheet
Dim varRange1, varRange2 As Range
Dim varTempString, varTempString2, varTempString3, varTempString4, _
varTempStringLeft, varTempStringMiddle, varTempStringRight As String
Dim varNLoop, varNLoops, varSpace1, varSpace2, varChar As Integer
Set varWorksheet = ActiveSheet
Set varRange2 = varWorksheet.Range("C1:C2")
For Each varRange1 In varRange2
varTempString = varRange1.Formula
varNLoops = (Len(varTempString) - Len(Replace(varTempString, "+", ""))) + 1
varTempString2 = varTempString
For varNLoop = 1 To varNLoops
varSpace1 = InStr(1, varTempString, "A1")
varSpace2 = InStr(1, varTempString, ",")
varChar = varSpace2 - varSpace1
varTempString3 = Left(varTempString2, varSpace1 + varSpace2)
varTempStringLeft = Mid(varTempString3, 2, varSpace1 - varChar)
varTempStringMiddle = "A" & varNLoop
varTempStringRight = Mid(varTempString3, varSpace1 + _
varChar, Len(varTempString3) - (varSpace1 + varChar - 1))
varTempString4 = varTempString4 & varTempStringLeft & _
varTempStringMiddle & varTempStringRight & "+"
Next
varTempString4 = Mid(varTempString4, 1, Len(varTempString4) - 1)
varRange1.Formula = "=" & varTempString4
varTempString4 = ""
Next
MsgBox ("You are successfully changed the ranges.")
End Sub