Track changes in excel against previous version vba - vba

Question

I am trying to track the changes made in an excel file used by multiple people. So far I have built the model (with help from stackoverflow) to save a version of itself within activeworkbook.path & "\Version Control".
The copy is saved when file opens and is named: date & time & activeworkbook.name
Currently it look at a range to determine if intersect then return the new value in sheet x cell y. How do I write the code to allow it to open the latest saved backup and give me in sheet x cell z the older versions value?
Code I have:
Track Changes:
Private Sub Worksheet_Change(ByVal Target As Range)
If Sheets("UserLog").Cells(1, 24) = IsBlank Then Exit Sub
Dim strAddress As String
Dim val
Dim dtmTime As Date
Dim Rw As Long
If Intersect(Target, Range("CheckRange5")) Is Nothing Then Exit Sub
dtmTime = Format(Now(), "YYYY-MM-DD HH:MM:SS")
val = Target.Value
strAddress = Target.Address
Rw = Sheets("UserLog").Range("D" & Rows.Count).End(xlUp).Row + 1
With Sheets("UserLog")
.Cells(Rw, 4) = strAddress
.Cells(Rw, 5) = val
.Cells(Rw, 6) = dtmTime
.Cells(Rw, 7) = Environ("Username")
.Cells(Rw, 8) = "SCI - SDBD"
End With
ActiveWorkbook.Save
End Sub
Saving the File:
Private Sub Workbook_Open()
Dim MyDate
MyDate = Date
Dim MyTime
MyTime = Time
Dim TestStr As String
TestStr = Format(MyTime, "hhmmss")
Dim Test1Str As String
Test1Str = Format(MyDate, "YYYY-MM-DD")
xxPath = ActiveWorkbook.Path
Application.DisplayAlerts = False
ActiveWorkbook.SaveCopyAs Filename:=xxPath & "\Version Control" & "\" & Test1Str & " " & TestStr & " " & ActiveWorkbook.Name
ActiveWorkbook.Save
Application.DisplayAlerts = True