DO NOT LAUNCH IT FROM A FRONT-END TO DO THIS, RUN THE GAME DIRECTLY FROM MAME!
Delete your nvram file, run the game. Push Tab, and go to the DIP settings. Flip the one to forget high scores (don't recall the exact terminology off hand). Go back to MAME, close the game and reopen it. Go back into the DIP settings and set the game to save high scores. This is let the rom fully re-initialize your nvram file. Alternatively, there MAY be something in the F2 settings, but i'm fairly certain that it was just in the DIP settings.
DO NOT LAUNCH IT FROM A FRONT-END TO DO THIS, RUN THE GAME DIRECTLY FROM MAME!
Doing this will put everything back to AAA, BBB, CCC, or whatever, and will allow you to properly save the records for the 100m dash and hurdles. As for getting the world records to lower than stock... good luck! Practice makes perfect, just develop your technique!