The code as it is, it inserts/removes columns based on a cell value. It works good, but it only copies the format of the cells from the first column and not formulas. I need for the following code to also copy the formulas from the previous column. Does anybody know what line I can add?

Option Explicit

Private Sub Worksheet_Change(ByVal Target As Range)
    
    On Error GoTo ClearError
    ' e.g. to prevent
    ' "Run-time error '1004': Microsoft Excel can't insert new cells because
    '  it would push non-empty cells off the end of the worksheet.
    '  These non-empty cells might appear empty but have blank values,
    '  some formatting, or a formula. Delete enough rows or columns
    '  to make room for what you want to insert and then try again.",
    ' which is covered for the header row, as long there is nothing
    ' to the right of the total column, but not for other rows.
   
    Const TargetCellAddress As String = "C2"
    Const TotalFirstCellAddress As String = "D4"
    Const TotalColumnTitle As String = "Total" ' case-insensitive
    
    Dim TargetCell As Range
    Set TargetCell = Intersect(Me.Range(TargetCellAddress), Target)
    If TargetCell Is Nothing Then Exit Sub ' cell not contained in 'Target'
    
    Dim NewTotalIndex As Variant: NewTotalIndex = TargetCell.Value
    
    Dim isValid As Boolean ' referring to an integer greater than 0
    
    If VarType(NewTotalIndex) = vbDouble Then ' is a number
        If Int(NewTotalIndex) = NewTotalIndex Then ' is an integer
            If NewTotalIndex > 0 Then ' is greater than 0
                isValid = True
            End If
        End If
    End If
    
    If Not isValid Then Exit Sub
    
    Dim hrrg As Range ' Header Row Range
    Dim ColumnsDifference As Long
    
    With Range(TotalFirstCellAddress)
        Set hrrg = .Resize(, Me.Columns.Count - .Column + 1)
        If NewTotalIndex > hrrg.Columns.Count Then Exit Sub ' too few columns
        ColumnsDifference = .Column - 1
    End With
    
    Dim OldTotalIndex As Variant
    OldTotalIndex = Application.Match(TotalColumnTitle, hrrg, 0)
    If IsError(OldTotalIndex) Then Exit Sub  ' total column title not found
    
    Application.EnableEvents = False
    
    Dim hAddress As String
    
    Select Case OldTotalIndex
    Case Is > NewTotalIndex ' delete columns
        hrrg.Resize(, OldTotalIndex - NewTotalIndex).Offset(, NewTotalIndex _
            - ColumnsDifference + 2).EntireColumn.Delete xlShiftToRight
    Case Is < NewTotalIndex ' insert columns
        With hrrg.Resize(, NewTotalIndex - OldTotalIndex) _
                .Offset(, OldTotalIndex - 1)
            ' The above range becomes useless after inserting too many columns:
            hAddress = .Address
            .EntireColumn.Insert Shift:=xlToRight, _
                CopyOrigin:=xlFormatFromLeftOrAbove
        End With
        With Me.Range(hAddress)
            .Formula = "=""""&COLUMN()-" & ColumnsDifference - 1
            .Value = .Value
        End With
    Case Else ' is equal; do nothing
    End Select
    
SafeExit:
    If Not Application.EnableEvents Then Application.EnableEvents = True
    
    Exit Sub
ClearError:
    Debug.Print "Run-time error '" & Err.Number & "': " & Err.Description
    Resume SafeExit
End Sub

Thanks beforehand!