Solved The Action button for respond or quite or edit gives Error

Why you two menu items in your main menu pointing to Kunena ?

the first menu (Theforum) is from the first install kunena .
the last one is from restore menu via kunenatools.
but if it's in there I'd like to hear it and indeed 2 menus is not necessary.
But it's a test site so adjustments are no problem

Hello,

I have seen that you have removed the wrong menu item in your main menu, so now the error when you use reply/quote are disappear

I deleted the kunena forum menu items anyway then have the kunena menu built up again via tools.
Still not working properly and after some more searching and comparing with another joomal4 with kunena .
i saw strange things in my kunena category settings adjusted these and above expectations now edit qoute and answer buttons seem to work without error messages.

In which language do-you have wrote on our screenshots ?

There is another issue on your issue, when i try to open a topic which is unread it gives me an error page :

404 View not found [name, type, prefix]: topic, html, site

I haven't changed any language settings now if all is well site and administrator are in English language. but the message that I myself as a test post there in my forum is Dutch (or is that not what you mean)
A I get it I had made messages with user Ashley But when I log in as adminleendert, I also get an error
I also did Synchronize Users but it doesn't help either so maybe i have a setting wrong somewhere so that others not users can do nothing?