Once you've created a KeepandShare account and logged in for the first time, the user name of the account cannot be changed.
If you really need a different account name, the one thing we can suggest is to create another new KeepandShare account with a new name that you want, and leave the old account behind - being careful to transfer (copy and paste) any information over from the old account to the new account that you want to preserve.
There is no problem having multiple accounts since they are free. (you might want to unsubscribe the inactive accounts so you don't receive occasional email updates from them).
( change username; change user name; change my username; change log in; change login; change user account name)