Welcome to MrExcel - you could use an event macro to insert the current date after each change.
<font face=Courier New><SPAN style="color:#00007F">Private</SPAN> <SPAN style="color:#00007F">Sub</SPAN> Worksheet_Change(<SPAN style="color:#00007F">ByVal</SPAN> Target <SPAN style="color:#00007F">As</SPAN> Range)
<SPAN style="color:#00007F">Dim</SPAN> c <SPAN style="color:#00007F">As</SPAN> Range, LastDateChangeRow <SPAN style="color:#00007F">As</SPAN> <SPAN style="color:#00007F">Long</SPAN>
Application.EnableEvents = <SPAN style="color:#00007F">False</SPAN>
Application.ScreenUpdating = <SPAN style="color:#00007F">False</SPAN>
<SPAN style="color:#00007F">For</SPAN> <SPAN style="color:#00007F">Each</SPAN> c <SPAN style="color:#00007F">In</SPAN> Target.Cells
<SPAN style="color:#00007F">If</SPAN> LastDateChangeRow <> c.Row <SPAN style="color:#00007F">Then</SPAN>
LastDateChangeRow = c.Row
Cells(c.Row, "Z") = <SPAN style="color:#00007F">Date</SPAN>
<SPAN style="color:#00007F">End</SPAN> <SPAN style="color:#00007F">If</SPAN>
<SPAN style="color:#00007F">Next</SPAN> c
Application.ScreenUpdating = <SPAN style="color:#00007F">True</SPAN>
Application.EnableEvents = <SPAN style="color:#00007F">True</SPAN>
<SPAN style="color:#00007F">End</SPAN> <SPAN style="color:#00007F">Sub</SPAN>
</FONT>
The above untested code should put the current date in each changed row's column Z.