[HMBeaty]

In your footer, find:

    <if condition="$show['quickchooser']">
        <td class="tfoot">
            <select name="styleid" onchange="switch_id(this, 'style')">
                <optgroup label="$vbphrase[quick_style_chooser]">
                    $quickchooserbits
                </optgroup>
            </select>
        </td>
    </if>

And around that, add:

<if condition="is_member_of($vbulletin->userinfo, x)"></if>

And replace x with the usergroup(s) that you want to allow to change the styles