Since yesterday i have the 'problem' that posts from a topic are not shown anymore. Only the first Post from a thread is shown, all others are a list at the bottom where i have to click each individually if I want to read them.

I haven't changed anything by myself, I think it changed to this when i followed a result from google. Haven't found the options in my control panel to change this back to the "display all posts available in a thread" option.

From what you are describing it looks like you have topics display mode set to Outline.

At the top right of the first post in a topic/page you will see two tabs, "Rating" and "Options". Select "Options" and a menu will appear, under "Display Modes" choose "Linear+"...

Ted.

Thank you very much for your fast and accurate answer - problem sovled.