Thanks for the reply!
Yesterday I submitted my RSS Feed to iTunes, and today I got it approved. Unfortunately no å, ä and ö in the description of the pod or info about the episode. I have tried to switch to WP's own theme and to turn off all plug without result. WordPress is upgraded to the latest version but the installation is 10 years old.
In wp-config.php I
define(‘WPLANG’, ‘sv_SE’);
/ ** Database Charset to use in creating database tables. * /
define ('DB_CHARSET', 'utf8');
define ('DB_COLLATE', 'utf8_unicode_ci');
In phpMyAdmin
Server connection collation utf8_general_ci
How do I do now?