First of all - do you really want dynamic groups? I think you just want groups.
In any case, the groups dropdown is populated by looking at what groups are defined on other pens - not which groups are marked as being dynamic.
That is - just type in your group name manually for one pen, and then it’ll appear in the dropdown for other pens.
Lastly - if you don’t really want the groups to by dynamic (dynamic groups means that that group will have its own piece of custom WHERE clause associated with it), remove them from the Dynamic Groups tab.