Hi there, the only way for us to change a username is if you re-make the account. Sorry about that.
Also I think I should add that we don't allow traps on the server and we ask that you keep passive mobs to a reasonable number (around 10 or so, no need to go overboard with anymore then that). If a passing by admin sees a huge excess of animals in a pin, they will probably trim down the heard.
As for the whitelist, please confirm you have gone over the rules
and we'll add you to the whitelist.