[webizen]

You may try the following rules:
%

Options -MultiViews
RewriteEngine On
RewriteBase /forums/
###########################################
# For LiteSpeed public cache (guest user)
###########################################
RewriteCond %{REQUEST_METHOD} ^HEAD|GET$
RewriteCond %{HTTP_COOKIE} !member_id= [OR]
RewriteCond %{HTTP_COOKIE} member_id=0
RewriteCond %{REQUEST_URI} !^/forums/admin
RewriteCond %{REQUEST_URI} !(css|js|png|gif)$
#RewriteCond %{QUERY_STRING} ^$
RewriteRule .* – [E=Cache-Control:max-age=360]

RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /forums/index.php [L]

Make sure to put non-cacheable URLs in Do-Not-Cache box.

Also enable rewrite logging to troubleshoot.