Changing all the 'x' letters to 'x#' ( all A's into A#'s ... )

I have made a blues and my version of He's a Pirate. ( from Pirates of the Carribean)
I'd like to put He's a Pirate into blues. which means changing all the A's into A# etz. etz.

Is there a function to change all the letters in your piece into another one?
(all A's into A#'s for example ).

Yes? Where is it?
No? OOF!

comment below please.