The code you had originally referenced two columns N and O. You changed that in the autofill statements but you still have code that references columns N and O, for example.
Selection.Style = "Percent"
Perhaps that's what your needing to do in your code or perhaps it's not, I don't know....
I was just pointing out that just as you changed the N and O references in the autofill statement then, if you need to do the same with the rest of the code, then continue to use Application.Selection as the range.
If on the other hand your code always changes column O to percentage then you don't need to use Application.Selection.Style.