can i change my username?
thanks
No, you can't. See the Questions&Answers, e.g.
de.lichess.org/qa/1616/can-usernames-be-changed.
I think this is a great idea for a fundraiser for lichess. If members could change their handle for $5 US I bet a lot of people would do it, I've seen this feature on a few other BBs, I don't think it'll pay for the servers but every little bit of extra $$ helps.