changing H2 titles

Dear All,

when I try to change a H2 on one of my pages – you know, that is called “title” it also changes the main H1 and the a´other H2 titles as well. Eg wehn I write as text of the new H2 title “test” all the other H1 and the H2s on this page read now test as well. What am I doing wrong? Please see the page “Leistungen” on my Website There you see that the H1 and all the H2s have the same name If I change one, all of them change.

Link to pic: https://ibb.co/c317Gyf

How can I solve that?

Thank you and BR

Angelika

The page I need help with: [log in to see the link]