Apache server

• Create a new file called .htaccess in the root dir of phpFox. 
• Goto AdminCP -> Settings -> Short URLs, copy htaccess rule then paste to file .htaccess
• Click to button "Enable Short URLs"
• This rule works in most apache servers. If it does not work, you can try this rule:

RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
RewriteRule ^index.php/(.*)$ [L]

• If it still not working, you can submit a ticket, so we can check detail on your server

Nginx server

After follow this tutorial Install phpFox on nginx server, you just goto AdminCP -> Settings -> Short URLs, then click to button "Enable Short URLs".