Resident Evil 5 (PC/Gold Edition), the native "green crosshair" for mouse and keyboard users is a common complaint. While controllers use the classic laser sight by default, PC players typically require a community patch or mod to restore this feature. Steam Community Recommended Mods for Laser Sights
If the settings menu doesn't fix it, you will need a community-made patch. Resident Evil 5 Laser Sight Mod Download