You have to edit your welcome_headers template. I have different ones for several user groups, such as:
PHP Code:
<if condition="is_member_of($bbuserinfo, 13)">
<!-- email verification not completed -->
<br />
<table class="tborder" cellpadding="$stylevar[cellpadding]" cellspacing="$stylevar[cellspacing]" border="0" width="100%" align="center">
<tr>
<td class="alt1">
<phrase 1="$vboptions[bbtitle]">$vbphrase[email_verification_not_completed]</phrase>
</td>
</tr>
</table>
<!-- / email verification not completed -->
<else />
<!-- email address not valid -->
<if condition="is_member_of($bbuserinfo, 18)">
<br />
<table class="tborder" cellpadding="$stylevar[cellpadding]" cellspacing="$stylevar[cellspacing]" border="0" width="100%" align="center">
<tr>
<td class="alt1">
<phrase 1="$vboptions[bbtitle]">$vbphrase[email_address_not_valid]</phrase>
</td>
</tr>
</table>
<!-- / email address not valid -->
<else />
If I remember correctly, you have to make phrases such as I did for
[email_address_not_valid] above.