When typing ^ i have to type twice to get that symbol in Xfce

I use Debian testing with XFCE as desktop environment. I have a german keyboard and sometimes use ^ (circumflex). When I hit that key once, the symbol is shown with an underscore. I have to hit it again to get rid of that underscore. I assume this is to get symbols like ⁴ etc., but I don't want that functionality, I never use it. But I don't know where I can turn it off. Can anyone tell me how to turn that off in xfce? At the moment I hit that key four times to show ^^ but that's annoying! edit: as requested: oli@DESKTOP-SJIB21T:~$ locale LANG=de_DE.UTF-8 LANGUAGE= LC_CTYPE="de_DE.UTF-8" LC_NUMERIC="de_DE.UTF-8" LC_TIME="de_DE.UTF-8" LC_COLLATE="de_DE.UTF-8" LC_MONETARY="de_DE.UTF-8" LC_MESSAGES="de_DE.UTF-8" LC_PAPER="de_DE.UTF-8" LC_NAME="de_DE.UTF-8" LC_ADDRESS="de_DE.UTF-8" LC_TELEPHONE="de_DE.UTF-8" LC_MEASUREMENT="de_DE.UTF-8" LC_IDENTIFICATION="de_DE.UTF-8" LC_ALL= The keyboard model in use is "Generic PC-Keyboard with 105 keys" and the layout was "use system settings". Now it is "Deutsch (ohne Akzenttasten)", with those settings it works.