Dell Audio by MAXX isn't working with external soun card

Hi, I'm using my Dell Inspirion 15 7537 with Win 8.1
I bough external audio interface/sound card Focusrite Scarlett 2i4.
I installed the drivers and all Inputs/Outputs work fine whe they are set in Windows Audio manager.
But in the Dell Audio app (came with Windows) I can't change any settings, Sound doesn't change at all.(Looks like the settings change the internal souncard output, but not the external:()
I love this Dell Audio application with EQ etc. But can I use it with my external USB sound card ?

Thanks!
David from Czech rep.