I can't change the resolution or switch to full-screen mode

Thanks for checking all of that ZeTerBerk​ 

If you're using an NVIDIA GPU, one workaround reported by other players is to check:

NVIDIA Control Panel > Manage 3D settings > Program Settings > Battlefield 6 > Automatic display switching

If that option is enabled, try setting it to Off, apply the change, then restart the game and test the display settings again.

This isn't a confirmed fix, but it has helped some players with very similar fullscreen/resolution issues.

I've tried everything. None of it helps.

Hey ZeTerBerk​ 

A few things worth checking:

1. Go to Windows Settings > System > Display and note the resolution and refresh rate currently selected.
2. In Battlefield 6, make sure the Fullscreen Resolution and Refresh Rate match those Windows settings.
3. Use Reset Category in the Graphics settings, restart the game, and then try changing the Display Mode and resolution again.
4. If you use more than one monitor, temporarily test with only the main display enabled.
5. Also check whether any software such as GeForce Experience/NVIDIA App, AMD Software, or another display utility is automatically applying game settings.