2 functions one cell

Hi Guys,
Im brand new here, 1st post hope you can help.

I have a workbook with a series of values i want to copy across. Its for monthly payroll
eg Cell H6 displays the value in A6 (=A6) (salary in feb is the same as in Jan)
Cell O6 displays the value in H6 (=H6) and so on. (salary in march is the same as feb)

If i amend a salary in march this copies acros subsequent months which is great, but if i then amend the salary from a previous month (say jan) this only copies as far as march as I have overtyped the formula.

Is there a way to allow me to overtype a value so subsequent months copy, but if i subsequently change a value in a month prior, the formula will once again copy right across the sheet?
I hope that makes sense,
Thanks in advance,
Joe

Hi Glenn,
I think you are correct about VBA, i saw an answer to another thread that suggested this and it looks like what I need but i couldnt figure out how to get the code to work on my workbook.
thanks for your answer.
Joe