How to post in Facebook groups so my friends wouldn't see it in their feed?

[Coffe Inn]

I belong to many groups on Facebook and I post comments there or start discussions. However, my friends don't belong to any of those groups and they are annoying me by asking me questions about my activity on those groups. I don't want them to know if they don't belong to those groups, but they said that they can see all of my group comments all over their Facebook feed. How to become more private so my friends wouldn't see what I post or comment there?

[Alfie J Lee]

Change your post privacy by selecting 'Group only' it's found under the status bar.

[pri✍]

Your posts, comments/likes in an OPEN Group, as the name 'Open' suggested means it's Public, might shown in your friends' Newsfeed, depends on FB algorithm for each friend; it will sure be revealed to your friends who put you in their Close Friend list.
There's no way around it.

Other than that, everybody in FB can find out what Groups you're a member of, all type of Group, yes, even your Secret Group.
Then they might open your Open Group you're a member of, and read everything there themselves.