Just to make sure I understand this correct:
You mean, I should add this to every Css file of the JS-Support-Plugin?

Thanks for the help buddy  

Cheers

Hi,
Not in every Css file of the JS-Support-Plugin
Add this css in any css file of the JS-Support-Plugin
.js-col-xs-12.js-col-md-12.js-ticket-wrapper {
   width: 48% !important;
   float: left !important;
   margin: 0 1% !important;
}

I'm afraid my english is nnot that good, but I really cant see the difference, I'm sorry. May you can tell me what css files you mean exactly?

Hi,
At the end of this file add that code./wp-content/plugins/js-support-ticket/includes/css/style.css
you can access this file using cpanel or ftp.
.js-col-xs-12.js-col-md-12.js-ticket-wrapper {
   width: 48% !important;
   float: left !important;
   margin: 0 1% !important;
}
Or follow instructions on this page
www.wpbeginner.com/plugins/how-to-easily...your-wordpress-site/

Huge Thanks! Works pretty good. 
Problem now is, that some Ticketfields are larger than others, so there are spaces between them because the Subject is too long (See Attachment). May I can set a maximum length for the Subject-Field? 

Thanks a lot for the always really quick help, I really appreciate this.

Cheers
Silvan Armbruster