The trainer screen usually shows which keys toggle which cheats.
Ensure you have the correct version. If you own a later version (e.g., Ultimate HD Edition), you cannot downgrade easily without specific patches. --- Download Trainer Resident Evil 4 Pc Version 1.0.0 Free
When players search for a they are specifically looking for a tool compatible with the "Day One" or launch build of the game. If Capcom has since updated the game to version 1.0.1 or higher, a trainer designed for 1.0.0 may crash the game or fail to activate because the memory addresses in the code have shifted. The trainer screen usually shows which keys toggle