Different representations of fonts / content

Hi, I'm using WP, CatchBox and the Media Gallery for quite some time. A longer time ago I experienced different representations in the editor and the articles. When inserting a picture in an article WP adds a grey frame and adds the caption of the picture - OK When viewing this article later on the caption get an added dash and a wrong font (something with serif) Where and how can I solve this? What do I need to edit? https://temp.mindtrips.de/pics/WP-Galerie.png shows the differences or https://www.mindtrips.de/urlaub/urlaub/ for a live view...