Hi, I've been looking at this today as don't have access to the PHP code. I had a simple quiz with Yes/No drop down - I wanted it to always display Yes/No but Moodle was helpfully changing this to No/Yes when the answer was no. Here is the very simple code I ended up using to get round this. Actually can't believe how easy it ended up being so I hope this helps and saves someone else similar pain!
Coins are made of metal: {1:MC:=Yes~No}
Banknotes are sometimes made of potato peelings: {1:MC:Yes~=No}
Basically put the '=' sign before the correct response and you can choose your order. If you want the answers to shuffle change the prefix to 'MCS'.