there's not enough information to determine what should be used but you can try:
instead of _level0
Okay, if I was going to change _level0 to _parent how exactly would I go about doing that?
I feel like I've been through Flash Professional front to back several times, and have yet to find a place where I can change any script.
why can't you change any script?
Primarily because I don't know how to access the script to make the changes.
the actionscript is either in the fla and/or in .as files. if you find any actionscript in the fla, you can change it using flash cs pro. if you find actionscript in an .as file, any text editor (or flash pro) can be used to make changes.