It should actually just be in FORUMHOME.
Search for
Code:
<td class="thead">$vbphrase[threads]</td>
<td class="thead">$vbphrase[posts]</td>
and then put a width="xxx" in each of the td's in that group of table cells.
I don't think you need to edit the forumhome_forumbit templates because the td's should follow the width you set in the FORUMHOME template.
At least that how it works in my style. It's modified quite a bit though.