Help with Activate code when file opens

[rizmomin]

Hello:

Please refer to attached file.
I am using below code to put the formula in cell N1 when "Final"Sheet is activated.
It works fine when i go to other sheet and come back to "FINAL" Sheet.
But let me give you scenerio where it needs to work but does not work.

Select say May18 from dropdown liast in cell N1.
Save the file and reopen.
Now when you open the file, it will not activate below code and hence you will see last saved version, in this case N1 will show May18 but i needed, N1=M1

Private Sub Worksheet_Activate()
Range("N1").Formula = "=M1"
End Sub

Let me know if you have any questions.
Thanks.