(Not a Teacher)I'd write it ,"....mix and edit it the way you like." 'That' isn't wrong, but isn't strictly necessary either.Also, "put the sound in the PC" doesn't sound quite right.Perhaps it should be something along the lines of, "....record the sound on your PC, then mix and edit it the way you like."You could also say "however you like" instead of "the way you like".
the way which you like' sounds unnatural to me.
In my opinion, if a native speaker said it is unnatural to me, it is wrong.
My understandin is that that and which can be used interchangeably as relative pronoun.
Am I wrong, in your opinion?
Some claim that in defining relative clauses only 'that' is correct. I do not agree, but I do feel that 'that' (or a zero relative pronoun) frequently sound more natural; they are certainly far more common.