Stop dispaying list of E-newsletter groups to logged in users

Hello,

I encountered this small problem on E-newsletter groups.

For logged in users there is an button for them to subscribe to the newsletter. But after pressing the button it shows available groups to subscribe into. I feel this is redundant and I don't want to display the list of groups to any user. They should by default be in the main subscribers group.

I already checked the Default Groups option in settings but it seems not working.

Screen shots are attached.

Highly appreciate any help.