If you've done what Strange said above and the move was executed successfully, you just want more particles in the move. I'm afraid that is not possible to do in the configuration. The amount of particles in a move is determined by the move developers, then they decide to put an option in config or not. I do, however, know a special place where you may be able to find a better version. There is another version of lightning (
here) created by Finn_Bueno. It is similar but has a bit more "pizazz" as far as the animations go. It has a slightly different animation and a different sound. I think it may be what you're looking for! To upload the ability, go into your Project Korra file, click on the Abilities folder, and add the lightning download there. Reload the project korra plugin or restart/reload your server and it should be added. If something is funky after you do that, the move isn't working correctly, then try disabling the ORIGINAL lightning in the Project Korra config.yml. Hope this helped!