As far as I remember, someone on this forum told me you're stuck with Word's choice of colour for bubbles … When I have to mark up/edit Word source files, I use character styles for new/deleted text and a separate paragraph style for comments I add. (instead of bubble comments, I mark the questionable text with a character style and repeat it at the start of the comment paragraph) Ctrl+Alt+s makes it relatively easy to apply the styles.

When edits are accepted, Find/replace quickly removes comment paragraphs and !delete text; select all – if I'm feeling confident – or select marked text and ctrl+spacebar then clears the !new character style.

It's a bit of extra work, but if it keeps the client happy and coming back for more … side benefit: it means I hand over a document with unaggressive new/deleted markup in green and grey and that's what the reader sees. With default "track changes", I could set set my own PC to give me this but the client saw her own defaults in screaming red. Not encouraging for her!