Change link in menu

Hi.

I want to change the name of a link in the menu. But as soon as I do it, all widgets of the page disappear.

https://testing.imabis.com/produkte/28-2/

this link should be renamed to

How can I do it without having to build everything from scratch??

Thank you!

Hello,

Please check this WordPress Codex page:
https://codex.wordpress.org/Using_Permalinks

Please feel free to ask any other questions that you might have.

Kind Regards, Roman.