Auto insert date, time & user in columns when data is entered in another column?

This might work

Right click sheet name. Then Select view code and paste in th below

Private Declare Function apiGetUserName Lib "advapi32.dll" _
    Alias "GetUserNameA" (ByVal lpBuffer As String, nsize As Long) As Long


Function fOSUserName() As String
' Returns the network login name
Dim lngLen As Long, lngX As Long
Dim strUserName As String
    strUserName = String$(254, 0)
    lngLen = 255
    lngX = apiGetUserName(strUserName, lngLen)
    If lngX <> 0 Then
        fOSUserName = Left$(strUserName, lngLen - 1)
    Else
        fOSUserName = ""
    End If
End Function


Private Sub Worksheet_Change(ByVal Target As Range)
If IsDate(Target) = True Then
If Target.Column = 4 Then
ActiveCell.Offset(-1, -3).Value = Date
ActiveCell.Offset(-1, -2).Value = Time
ActiveCell.Offset(-1, -1).Value = fOSUserName
End If
End If
End Sub

VBA Noob