How to change Unreal Tournamnent's Pre Alpha resolution outside the game?

I would like to know which is the game file to switch the resolution since I can’t change it in game. Thanks in advance!

FIXED* Tried and Tested*

Documents>Unreal Tournament>Saved>Config>WindowsNoEditor>GameUserSettings

GameUserSettings > ResolutionSizeX=1280 ResolutionSizeY=720 Save. Start Game, set to your actual resolutions in game.

NOTE* If your ResSizeXY were already at 1280/720, try setting it to something lower but generic.