Dynamically Filter Line Chart with Formula Queries (or open to better ideas to do this)

Can you tell us a little more about the structure of your app. You may not have relationships, but what are the records that are holding these totals and what are the formulas queries summarizing? What are the sort of child tables. 

Well, I gather from your question that your chart is simply a report of opportunities. So it's just filtering which opportunities will show.

You don't need formula queries for this. Build the charts right on the Opportunities table and let a dashboard filter handle switching contacts.

Add two formula - text fields on Opportunities, one for the month and one for the year the opportunity was created:

Right("0" & ToText(Month(ToDate([Date Created]))), 2)

ToText(Year(ToDate([Date Created])))

Make a line chart with the month field on the x axis, a count of opportunities on the y axis, and the year field as the Series. Each year becomes its own colored line, so this year, last year and two years ago sit on top of each other. Filter the report to the last three years.

Make a second line chart the same way with your revenue field summed on the y axis. Keep them as two charts. Series isn't available on a dual y axis chart, and count and revenue are on very different scales anyway.

Put both charts on a dashboard and add a Text filter on the contact field, applied to both reports. In the meeting he picks the contact at the top of the dashboard, both charts update, and he switches to the next person.

https://help.quickbase.com/docs/get-data-into-bar-line-and-area-charts 

https://help.quickbase.com/docs/quickbase-using-dashboards