[B00MER]

Edit skin1/modules/Extra_Fields/product_modify.tpl:

{* $Id: product_modify.tpl,v 1.4 2003/02/18 09:33:11 svowl Exp $ *}
{section name=field loop=$extra_fields}
<tr> 
  <td class=ProductDetails height="11">{$extra_fields[field].field}</td>
  <td class=ProductDetails height="11"> 
    {*<input type="text" name="param0{%field.index%}" size="24" value="{if $product.productid eq ""}{$extra_fields[field].value}{elseif %field.index% eq 0}{$product.param00|escape}{elseif %field.index% eq 1}{$product.param01|escape}{elseif %field.index% eq 2}{$product.param02|escape}{elseif %field.index% eq 3}{$product.param03|escape}{elseif %field.index% eq 4}{$product.param04|escape}{elseif %field.index% eq 5}{$product.param05|escape}{elseif %field.index% eq 6}{$product.param06|escape}{elseif %field.index% eq 7}{$product.param07|escape}{elseif %field.index% eq 8}{$product.param08|escape}{elseif %field.index% eq 9}{$product.param09|escape}{/if}">*}
    <TEXTAREA name="text" name="param0{%field.index%}" COLS=25 ROWS=5>{if $product.productid eq ""}{$extra_fields[field].value}{elseif %field.index% eq 0}{$product.param00|escape}{elseif %field.index% eq 1}{$product.param01|escape}{elseif %field.index% eq 2}{$product.param02|escape}{elseif %field.index% eq 3}{$product.param03|escape}{elseif %field.index% eq 4}{$product.param04|escape}{elseif %field.index% eq 5}{$product.param05|escape}{elseif %field.index% eq 6}{$product.param06|escape}{elseif %field.index% eq 7}{$product.param07|escape}{elseif %field.index% eq 8}{$product.param08|escape}{elseif %field.index% eq 9}{$product.param09|escape}{/if}</TEXTAREA>
  </td>
</tr>
{/section}

Copy paste that into it replace its entire contents