You may try the following code for bb_plugins.php:
$genViewlastdiscussions=20;
if($page==PAGE1_OFFSET+1) $viewlastdiscussions=10; else $viewlastdiscussions=$genViewlastdiscussions;
if($action==''){
$totalForumsTopics=0;
if($cols=db_simpleSelect(0,$Tf,'forum_id, topics_count')){
do{
$forum=$cols[0];
$disallowedForums=getAccess($clForums, $clForumsUsers, $user_id);
if( (isset($lastOut) and in_array($forum, $lastOut)) or (is_array($disallowedForums) and in_array($forum, $disallowedForums) ) ) {} else $totalForumsTopics+=$cols[1];
}
while($cols=db_simpleSelect(1));
}
$pageNavExtract='';
if(!isset($disableNavDisplay) and $totalForumsTopics>0){
if($sortBy==0){
if(isset($mod_rewrite) and $mod_rewrite) {
$urlp=$main_url; $urlType='Extranavmr';
}
else {
$urlp="https://www.minibb.com/forums/{$indexphp}"; $urlType='Extranav';
}
}
else{
$urlp="https://www.minibb.com/forums/{$indexphp}sortBy=1"; $urlType='Gen';
}
$pageNavExtract=pageNav(PAGE1_OFFSET+1,$totalForumsTopics, $urlp,$genViewlastdiscussions,FALSE,$urlType);
}
if($pageNavExtract!='') $mbpn='<br />';
}
then for
templates/main_last_discussions.html or
templates/main_modern_layout.html, instead of {$pageNavExtra}, you should paste:
{$pageNavExtract}
This solution will take an additional, still very lite request to the database, and it's a bit dirty, 'cause this request will be later repeated in the script; but probably having such a requirement, you should not care about it.