Before posting any question I recommend to search forum. I've explained many times how does it works.
1. When JoomFish is installed JComments uses separate settings for each language you've on site. This is nessesary to allow to have different messages, comments rules for each language. And this behavior could not be disabled. All you need is setup JComments for each language (when JoomFish is installed you will see additional select box with language in JComments settings section).
2. When JoomFish is installed all comments are separated by language. If you have 2 languages (EN and FR), when you're reading English article you'll see comments leaved for this article and for this language, when you'll switch to French you will see comments leaved there. But you can disable this behavior with small trick. See here for more details: How to disable multilang support in JComments?