Quickly select lines of certain colour

[RFoudy]

Hi all,


I have a large number of slides with different colour lines and want to change the colour of all the grey lines to blue. The colours would have been applied individually separate to any themes. I was thinking about using macros but I don't know enough about them to carry out the operation.
I have researched this online but to no avail, any help you can offer me is greatly appreciated.

Kind Regards,
Richard