Change colour of one part of a data series on lots of graphs at once

Hi there,

I have about 50 graphs, each copied into a tab in one Excel file. At the moment, I have several options plotted denoted by different colours (see sample file attached). Option 1a = blue, Option 1b = grey, Option 2 = yellow, Option 3 = orange. I would like to change Option 3 to green without having to do this manually on each graph. Please see sample file and let me know if you know a quick way of doing it. I'm not adept with VBA but feel that MAY be able to help?

Thanks in advance for any offers. I also need to complete this ASAP (in the next day or so) so any quick help would be really appreciated.