Screen shots are of little use to us for things like this. There are multiple causes of characters not being displayed correctly. This "looks" like it is probably the default theme, but we can't even confirm that much less guess what you have the site character set option set to.
Other issues are the character set of your file system and what character set is needed for URIs. Setup will have discussed these issues with you if you peruse the warnings. Suffice it to say if you have not made the recommended 'charset_tést' file there is no way for Zenphoto to know what it should be doing.
Comments
Try the encoding settings on the options, maybe your server is not UTF-8 but a specicic Polish based encoding setting.
Other issues are the character set of your file system and what character set is needed for URIs. Setup will have discussed these issues with you if you peruse the warnings. Suffice it to say if you have not made the recommended 'charset_tést' file there is no way for Zenphoto to know what it should be doing.