Trying to explain Dad's bills to him

When out to dad's this afternoon with Kayla.  I had Dad's bills all written out as easy as I could make it for him to understand, showing that with him only giving me the disability check to work with after I pay all bills it leaves only $4.88 in the account and when he writes anything rather than using his cash that he has available, which is over $500 per month for pocket cash, he runs the checking account short which in turn draws from a line of credit, which keeps running the balance up.  Can't get him to understand that he needs to let me handle paying all the bills and he just pay cash for anything that he needs.  He said NO he can't give up his independence.  I explained to him that it would happen to all of us at some point.  We I ended up getting upset.  I just need to go ahead and do what I know to do.