This is for most or all of the time:
Go to "MyDocuments"
Click on the folder "My Games"
Click on the folder "Halo"
Click on the folder "savegames"
Click on the folder that has your Halo profile's name on it
Then click on the folder "Checkpoints"
Open "autosave.sav" in Notepad (The one that is samller in file size)
Then edit how you want it.
This picture will help you.
Save it.
Open Halo go to Campaign then go to Load Game and load the appropriate game save.
