For multithreading you should use resources. There are additional
settings for each resource, just double click it inside resources pane.
There you can fine tune your settings to achieve desirable behavior.
In your case you should set resource to use each line only once,
and set max symultanious usages to 1. Check other settiings too
to make it work the way you want.
For those who needs this later, you can set up http proxy and send a simple get request to https://api.ipify.org , it will give you the ip adress in plain text, no need to parse the json.
One of many simple and easy ways to do it.
