respawnall to load up the new creatures that you edited. This will clear all the cached creatures from game. If it says 'loot=18010 60.04' then that means that particular item will drop 60% of the time, get it? You can add more loot= lines if you want just make sure you change the 'Total Items' at the top of that bosses list. loot_creatures_aq.scp) also found in your scripts\extra folders in the repack folder.
If you want to change the loot drop % or set what loot each boss drops then open your loot scripts (ex. If you want to edit bosses open the creatures_BHN.scp (scripts\extra) file and edit the bosses there.
There you will see 'maxhealth= #', thange that # to whatever you want. Ok to change the creatures Max Health open the creatures.scp file that is in your scripts folder (in repack folder).