How to get different change tracking colors for different authors

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LyX 2.3.2
macoS 10.11.6
PDF viewer Skim

When change tracking is enabled, insertions are shown in LyX as underlined blue and deletions are shown in a slightly lighter shade of crossed-out blue. But in the PDF, insertions are in blue, no underlining, and deletions are crossed-out red.

I’m on a second revision of a manuscript. I want to keep the changes from the first revision and also view changes to the second revision, but in different colors, both in LyX and PDF. I see that I could make myself the second author, as that author is set up for different colors. How do I do that? I see the Identity item in Preferences but it doesn’t seem to have any effect. And the docs seem a little shy on this topic, as far as I can tell.

BTW the manual says that to get changes to appear in the output one needs dvipost. Seems a little stale and no mention of PDF which output seems to appear without adding any packages.

Jerry