I think I may have it figured out. With a table open (in tuner pro) I use the multiply function, highlight the cell/cells I wish to change, and enter a multiply value; For example if I wish to change a ve value/s by a certain percentage, I enter a multiply value of 1.xx. Where xx is the percentage I wish to change by.
1.10 being +10%, 1.05 being +5% and so on and so on.
So, thought I would put a - in front of the 1.10 multiply function to see if it would subtract 10%. Nope, it multiplied in positive direction but changed the whole cell value to a negative.
Next I kept the 1.1 value in but selected divide. It subtracted from the base value, but not quite 10%, so I'm stumped.
Not sure how to use the smooth function though.