Where or how do I change the look of my Mobile version?
Looks fine in the Customizer but then totally different on the device.
Menu doesn’t work (not clickable and the blogpost are shown in fulll length instead of excerpt! 
Bummer! Any ideas?
I atteched the screenshot.
Hello @katharinao,
Thanks for writing in! In looking at your site live, it appears that you seem to be using some type of plugin that is completely altering the markup of the theme when it detects a “mobile” device is viewing it. X is mobile-ready out of the box, so you should not have any need for functionality of this type, and I would recommend turning of whatever plugin is outputting these problematic changes. If you must leave this plugin on for whatever reason, you will need to speak with the developer of this plugin as it is drastically altering the markup of your theme and it would fall outside the realm of product support here as the issue is being introduced on their end. Again, X is fully responsive out of the box and you should have no need for a plugin of this type anyway, so I would recommend turning it off and the theme should work properly for you.
Cheers!
Thanks for your quick help … it was jetpack … wink: A little sad but not as important as I thought 
No worries at all, glad you were able to get to the root of it!