我的Wordpress站点中的Polylang和永久链接

I install polylang plugin for multilanguage wordpress website and for better seo i want make diffrent permalinks . This is link for my site ;

link to my site

What i wanna to do is Main Site url for English and Polish version look like this

http://www.elefantti.iq.pl/

But for other subpages will be

www.elefantti.iq.pl/%postname%

How can i achive that?

Thanks for your answers!

Update!

I try edit my htacces file :

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
RewriteEngine On
</IfModule>

# END WordPress

This is what it look oryginaly and I add this : RewriteRule ^$ /strona-glowna/ [L]

And it dosent work , what i do wrong?