Hey! You have to edit GAME#.sav ('#' is 0 if you're using the first slot, 1 if second slot, etc.) starting from offset 0xBEEA, just like what c4388354 said. You can press ctrl+G and then type BEEA. The next 4 bytes are the values that you need to change.
Right here, it says FF FF FF 7F. This I...