separating groups of notes

I would like to group notes in a measure by their beat, such as:
8th note & 2 16th notes together, then 2 8th notes together, etc. I have looked at the documentation, but can not figure out how to keep the software from joining groups of notes to one beam. Any suggestions would be much appreciated. Also, is there a way to go back and separate groups of notes already input?

Thanks as always,
harris128