When you disable the Hud and Crosshair in Blood - Fresh Supply, both will reappear when you load a save or start a new level. The game ignores the menu settings.

It's caused by a glitch associated with the crosshair being disabled. If you leave the crosshair enabled and only disable the hud, your settings will hold, but the crosshair will be showing.

If you'd like to play without the hud and without the crosshair, you can use this mod from the Hud Free Gaming Wiki:

https://hudfreegaming.fandom.com/wiki/Blood