Screen resolution not saving, audio surround and mouse DPI questions

Running full tilt system. i9 9900k, 32GB, Win10 64-bit. , game is on a SSD 850EVO, MSI RTX2080Ti Gaming Trio 11GB, Realtek surround audio on a Gigabyte Z390 AORUS Master-CF MB., and a Asus PG27U monitor, Logitech true 5.1 surround setup, Logitech G903 mouse.

I have the game running at 4k. Whenever I start the game up, the screen has black borders on all sides. If I switch from FULL screen to any other screen mode, it’ll go back to being full screen picture with the change/cancel buttons on the screen. If I then cancel the screen change, it will stay at FULL screen with no borders.
Any ideas how to fix that? I thought it was because I was running HDR, but if I leave HDR off, it still does it. I have G-sync turned on as default in windows and monitor. I didn’t try disabling that.

Another issue I have is if someone in game is in front of me, his voice is loud and clear. The moment I turn left or right from that person, his voice is 80% softer coming out of any other speaker besides the center channel. Any way to fix that?

Lastly, and I seem to remember this with the old Borderlands games, but why is there such a big difference in DPI while in any screen with a menu. When running around, mouse works fine. The moment I TAB or ESC to any screen with a menu, it’s like my DPI is 50% less.

Ok, one more question. How do I set the driving mode to be with the keyboard A,S,W,D and my mouse to be like a turret look and shoot? At the moment, W is forward, but left and right is controlled with mouse and shooting together.

Skip the audio question. I got it work. Just after posting, a friend responded to have me check the windows surround sound. It was defaulted back to stereo. Once I reset it back to 5.1 and got into the game, the surround audio is working.