I used to know this, I'm sure I did

[flick]

It turns out that the most complicated and tedious part of renaming your LJ account is editing your years-old journal theme to change the username in the links.

(And, actually, not necessary as it redirects, but I like to have things nice and neat.)

I'm glad I could just do a find and replace on it, because I really can't remember how it works.