If you're unable to find any issues in the developer tools please use the link in my signature to PM me backend login credentials and will take a look as it failing to save the parameters suggest something is erroring.

The save is redirect back to the index page of backend. This typically means you're hitting max_input_vars limit. Looks like max_input_vars is set to a limit of 1000, but your form POST is hitting over 1300 due to many select options added to the field. You'll need to adjust php.ini and set max_input_vars to something like 3000 to get rid of the issue. if unsure how please contact your host as they should be able to help you do this.