Change in parent table to calculate in child

[Mattsshop]

OK, I have a quote builder for my small construction company that I am working on. I have a project table that I can put markup, per hour rate and tax percentage in. Then I go to estimate items and add each item with things like item, quantity and hours needed for each item. If I set the per hour rate to say $200 as in the example all my calculations work, but when I decide to change my hourly rate in the projects view it will not update to my total cost of previously added items in estimates form. It only applies to new ones.
I am thinking I need some way to trigger a recalculation on columns for previous items but I can not seem to find out how.

Thanks,
Matt