Remove Outside Filters

Hi,
I think the dax function that you would want to use is ALLEXCEPT, you can use this in the second part of a CALCULATE function to ignore all filters 'except' the specified column filter that you're interested in. 

In this case i think you would do something like CALCULATE(your expression, ALLEXCEPT(PersonTable, PersonID)) -- hopefully this basic example helps you. This would ignore the specific month column from the matrix and show all months to show the change over time but doesn't ignore the person you've selected from the matrix.

Find the microsoft document on the dax funciton ALLEXCEPT here: https://learn.microsoft.com/en-us/dax/allexcept-function-dax
This area is really useful for different dax functions.

Let me know if this helps 🙂