How to change the program language?

i have problem on one comp (german program language) to add new documents - it do not show the list of labels. On the other comp the program language is english there i have no problems. i wonder how i can change the language to english on my first comp - i tried to reinstall but it is always in german

new observations:
after the sixth installation (also in german) i saw that after i was waiting for some time then suddenly the Labels appear - so it seems it is a timing problem on that comp - on two other copmps no problem at all

As any other applications, Paperwork uses your system language.

The timing problem is a bit weird but may be related to disk access speed.