The first thing I did was use REW and measured several places in my room to find the proper placement. Then I did the same with the second one to get them both to cover what they could at my listening chair.
Next, in regards to the app settings, I started with the cross over in order to meld them with my towers, adjusted the volume level (this is a personal taste) and left the phase settings alone. Phase can be adjusted based on several factors and its a rabbit hole I never understood but its based on placement (side wall, back wall) and frequency compared to your mains. I hope someone can give you a better explanation in simple terms incase you want to tackle it. I turned off all the other enhancements (EQ, room gain etc.) because it made them boomy and muddy (again, personal preference). The only thing I use the app for now is the volume once and a while.
