My rendering mode option in Fortnite was not saved
If your selected rendering mode doesn't stay saved after restarting Fortnite, follow these steps to set it using command line options in the Epic Games Launcher.
Legacy Epic Games Launcher
Open the Legacy Epic Games Launcher.
Select the Settings icon next to your profile in the top-right corner.
Click Settings.
Scroll down and expand Fortnite.
Check the box for Additional Command Line Arguments.
Clear any existing command lines in the field.
Enter the command line that matches your preferred rendering mode:
DirectX 12: -d3d12 -sm6
Performance: -d3d12 -FeatureLevelEs31
Epic Games Launcher Preview
Go to Library.
Access the more options menu for the game.
In Grid view:
Hover over the game tile and click the 3 dots.
In Details view:
Select the game from the left sidebar menu. The game information will appear on the right side.
Click the 3 dots next to the Play button.
Select Manage.
In the Launch Options, activate the Additional command line arguments toggle.
Enter the command line that matches your preferred rendering mode:
DirectX 12: -d3d12 -sm6
Performance: -d3d12 -FeatureLevelEs31
Launch Fortnite.