Drop Down Issue - multi level filter

I have created a worksheet in which I want to Look up a function, and match it with the location and name.

Problem is, I will select a function from my drop down list, and it will show the individuals with that specific function. Now I want to select my Location dropdown, to see which employee is in a certain city. When I do this, My other dropdowns reset.

How do I get it not to reset itself?
Cheers

I hope I explained this properly. I have attached my template