Nebulus and DTech are right in saying that you shoud avoid global variables.
Refering to the other form's variables is one way to do it, but if you wanted to push it one step further, you would call a public sub or function on the other form to update its private variable(s) with the new one(s) you would pass as parameter(s). The public function on that second form would then do whatever logic should be down with the updated variables.

The point of this is that all the logic related to the updating is contained in a single place. Lets say that later you want to have another form update the summary fields, and that you had already added logic that, for example, wrote the summary in a sentence and displayed it on the summary form. On that new form you would only need to call that public sub/function of the summary form where all the displaying logic is contained.

Anyways, I hope I wasn't too confusing (it's late and I'm tired...)

Ammo