Once your experiment starts running, you’ll have the possibility of editing the variations and the conversion event.
But while the test is running, the changes won’t be accepted.
You have two ways of dealing with it:
You can reset the current experiment, losing all the progress for the current experiment.
Or you can save the changes and wait for the next experiment to start. When a new experiment is automatically created, it will take into account all saved changes.
Instead of editing the current experiment, you can also delete the webpage to start a new experiment from scratch.