Totally destroyed website every time i edit

Hi,
everytime i change the smallest things i get horrible results like this:
[video src="https://jeroch-verlag.de/screens/enfold-foobar.mp4" /]

That means:
Eeverytime i change something i need to
– delete the cache
– toggle “disable/enable merged CSS”
– delete my Browser cache
and
…the desaster is not only on my end — other people can see it to.
… the changes i made before i emptied the cache are gone

Next issue:
– I add an image
– The image is there and it can be called via rightclick
– But its not visible in the frontend
see screencast: https://jeroch-verlag.de/screens/enfold-nomage.mp4

This is very troubling.

Marcus

PS: No, sorry – i cant give you access but you have a lot of information now and tools like Firebug/Webinspector.