Teaching with Moodle

Hi Helen! The thing is, that I would like to be able to choose the right grouping in every activity. If I set the course to separate groups, the grouping is same throughout the whole course and I won't be able to choose the grouping in every forum. This leads to situation where students need to choose the right group themselves (see the pic attached). I have tried this once and it didn't go well: students posted on wrong forums and I got a massive amount of questions about unclear forums, even though there where good instructions on the forums. So that's why I'm looking for a solution where I could still be able to set the grouping in every activity.