If the preferences initials are changed, the comment flags in the score don’t update to reflect that, even on reload of the project (I had some accidental wrong initial in there originally, fixed it to get comment flags that are correct but it’s not propagating.)
And small point, but shouldn’t three characters be allowed for the initials? Initials can include the middle name in my experience, or could be used by people with hyphenated names.
It’s correct that existing comments don’t get updated if you change the username in Preferences. That’s as designed.
A couple of people have suggested that it would be helpful to allow three characters in the Initials field. This is something we may add in future.
as designed … oh OK, so if you want to tag the comments differently you can use this, or if several people (e.g. assistants) are using the same computer and instance. Verrrry clever.
You know I keep trying to find a bug in Dorico but you thwart me at every turn!
Why are you “trying” to find bugs? 
It was a “joke” on the fact that they have apparently no bugs
Heh, I wish Dorico didn’t have bugs. But I’m glad that on the whole most users don’t run into oodles of them every day. Our testing team work hard to find them before end users do, and where we possibly can we fix them before the software gets out into the wild.