[SOLVED] Change registration info icon text

Hi
I have set up the registration for new members so that they can enter a full name, with spaces, as their username, should they wish to do so, using the "multiple words with spaces" option that you provide in the username field. However, the info icon next to this field in the registration page still shows the standard message, telling potential members to enter a name with "no spaces, at least 3 characters etc".
I would like to know how to change this, to suit the option I have chosen.
Obviously it would be great of this text was linked to these options, so that alternative text displayed according to the choices made by admin? Maybe this is tricky to set up?
Thanks

Edit the username field and supply a custom description for the field. By default it's a language define, but you can replace it with your own text or own language string.

Thank you very much. That's really simple. I should have realised that was the way to do it.