Hit 'F2' to edit the cell.
Hit 'F4' to toggle through Absolute (what you want), Relative
Column/Absolute Row, Absolute Column/Relative Row, Relative (what you have).

FYI, Below is a subroutine called 'FormulaReferences_AbsoluteRelative' that
will cycle through those options for all selected formulas.

'/=============================================/
' Sub Purpose:  Toggle formulas in selected cells between
'       All Absolute, Abs Row Relative Col, Relative Row Abs Col,
'       and All Relative
'
'   xlAbsolute = 1
'   xlAbsRowRelColumn = 2
'   xlRelRowAbsColumn = 3
'   xlRelative = 4
'
Sub FormulaReferences_AbsoluteRelative()
 Dim iToAbsolute As Integer
 Dim iFromReferenceStyle As Integer
 Dim rngCell As Range, rngSelection As Range
 Dim strStatus_Cell As String
 
 'check for an active workbook
 If ActiveWorkbook Is Nothing Then
   GoTo exit_Sub
 End If
 
 On Error Resume Next

 'get previous value from registry
 iToAbsolute = _
   GetSetting(appname:="FormulaStatus", _
   Section:="Status", key:="Value")
 strStatus_Cell = _
   GetSetting(appname:="FormulaStatus", _
   Section:="Cell", key:="Value")
 
 If Err.Number = 13 Then iToAbsolute = 0
 
 On Error GoTo err_Sub
 
 'check if 'cell' is same as current active cell
 If strStatus_Cell = Selection.Cells(1).Address Then
   Select Case iToAbsolute
     Case 0
       iToAbsolute = 1 'absolute
     Case 1
       iToAbsolute = 2 'xlAbsRowRelColumn
     Case 2
       iToAbsolute = 3 'xlRelRowAbsColumn
     Case 3
       iToAbsolute = 4 'Relative
     Case 4
       iToAbsolute = 1 'absolute
     Case Else
       iToAbsolute = 1 'absolute
   End Select
  Else
   iToAbsolute = 1 'absolute
 End If

 Set rngSelection = _
   Intersect(Selection, _
   Selection.SpecialCells(xlCellTypeFormulas))

 'check for formulas, if none found, end procedure
 If rngSelection Is Nothing Then
   GoTo exit_Sub
 End If

 'add values to registry for next 'toggle'
 SaveSetting appname:="FormulaStatus", _
   Section:="Status", key:="Value", _
   Setting:=iToAbsolute
 SaveSetting appname:="FormulaStatus", _
   Section:="Cell", key:="Value", _
   Setting:=Selection.Range("A1").Address
 
 'find out what reference style is being used
 If Application.ReferenceStyle = xlA1 Then '1
   iFromReferenceStyle = xlA1
  Else
   iFromReferenceStyle = xlR1C1  '  -4150
 End If
 
 For Each rngCell In rngSelection
   rngCell.Formula = _
     Application.ConvertFormula(Formula:=rngCell.Formula, _
     FromReferenceStyle:=iFromReferenceStyle, _
     ToReferenceStyle:=iFromReferenceStyle, _
     ToAbsolute:=iToAbsolute)
 Next rngCell
   
exit_Sub:
 On Error Resume Next
 Set rngSelection = Nothing
 Exit Sub

err_Sub:
 Debug.Print "Error: " & Err.Number & " - (" & _
   Err.Description & _
   ") - Sub: FormulaReferences_AbsoluteRelative - " & Now()
 Resume exit_Sub

End Sub
'/=============================================/

HTH,