"Karen" wrote:
I need to increase my spreadsheet by 5% for 3 years

If you want to compute the increase in another cell, then in A2 (for
example):

=A1*(1+5%)

If you want to cause the numbers to be increased in existing cells, then put
=1+5% in some cell and copy it. The select the existing cells, right-click
and click Paste Special, click multiply, and click OK. You can now delete
the cell that has =1+5%.


and also some of my colums I need to show a decrease
of 5%.

Similar to the above, but use 1-5% instead of 1+5%.