The behavior is not the default behavior of the WPML language switcher because you added extra CSS code regarding that to this file (Your child theme CSS file):
wp-content/themes/hotel-xenia-child/style.css
Check the code from line 343 onward.
We will not be able to provide custom CSS coding service as it is outside of our support scope.
Thank you so far Christopher,
my problem is that the guy who developed the site for me is no longer available and I am trying to fix all the problems that are a result of some incompetence related to WPML.
I am only end user with no knowledge of CSS.
I tried to remove the whole section from line 343 to 411. but that did not made any difference.
Then I noticed an advanced Script and Style editor in the Theme options which had some code under Custom Java Script options. With this I played around a bit changing some values.
It did improve a bit but still not as it should be.
the code as it is now:
var li = jQuery('.wpml-ls-current-language');
var ul = jQuery('<ul/>', {'class': 'language-switch'}).append(li);